Search

Infrared soldering as a step in module encapsulation, which would cause light-induced degradation (LID) and light- and elevated-temperature-induced degradation (LeTID) effects on solar cells, may cause efficiency mixing among solar cells that were originally in the same grade within the module after soldering. Furthermore, the problem of bright and dark regions would appear, which would result in a decrease in the CTM value. Current injection is considered to be one of the effective methods to solve the above problem. However, after the current injection treatment, there is still a 10% probability of the appearance of bright and dark regions in modules. In this work, we first adopted the conventional current injection process in monocrystalline passivated emitter and rear cells (PERCs). The effects of injected currents, temperature and time were systematically optimized, and cells with or without the current injection under the optimal parameters were illuminated with 1 sun at 85 °C for 25 h. Secondly, a piece of equipment was developed to further stabilize the performance of solar cells and improve the CTM value. The results showed that the best current injection parameters were a temperature of 185 °C, an injected current of 11 A and an injection time of 770 s. Compared with the cells without any pretreatment, the relative changes in the η, Voc, Isc and FF of the cells pretreated with the optimal conditions mentioned above were 0.23%, 0.08%, 0.02% and 0.08% larger, respectively, after 25 h of degradation. Then, solar cells processed by current injection were processed with our equipment, and the probability of a problem occurring was reduced from 10% to 2%. Meanwhile, the CTM value increased by 0.4%. Finally, a balance mechanism between H0 and H0-X has been proposed to explain the mechanism of the equipment. [ABSTRACT FROM AUTHOR]

An important challenge in industrial laser ablation is laser-induced damage. In this study, reduced damage was achieved through the transition of the laser distribution from a Gaussian beam to a top-hat beam using diffractive optical elements (DOE), which overcome inhomogeneous irradiation. The higher peak fluence of a Gaussian beam far exceeded the ablation threshold and led to severely melted silicon at a higher depth covering the polished texture. The top-hat beam, with uniform irradiation, had a superior ablation characteristic and created a uniform square opening with the shallow melted silicon in the lift-off process. Thus, its effective minor carrier lifetime was 15.35% less at an ablated area fraction of 2% after re-passivation because of the decreased damage. After optimizing the ablation pattern with a top-hat beam, the local contacts improved the average open-circuit voltage (Voc) and short-circuit current (Isc) values of the cells due to the decreased damage and the uniform openings, but the damage induced by a Gaussian beam was too deep and can be partly restored under back surface field (BSF) formation. The overall increment in Isc and Voc enhanced the average efficiency by 0.05% of the absolute value for the PERC cells and 0.03% of the absolute value for bi-facial PERC cells. [ABSTRACT FROM AUTHOR]

To further enhance the mechanical endurance of ZnO–Cu–ZnO (ZCZ) films and CuZnSnS (CZTS) solar cells with deposited ZCZ films (ZCZ CSCs), Ag elements were introduced into metallic layers of ZCZ films using magnetron sputtering Cu–Ag co-sputtering techniques. The Ag addition effectively reduced the stresses generated during the growth of the Cu film, resulting in the suppression of three-dimensional island growth and the formation of a more uniform metallic film. Specifically, ZnO–Cu/Ag(35 W)–ZnO (ZCA35Z) films exhibited an average transmittance (T -ave) of 89%, outperforming the ZCZ film with a T -ave of 80%, achieved by increasing the continuity of metallic layers. Moreover, ZCA35Z CSCs demonstrated a higher power conversion efficiency (PCE) value of 6.38% compared to ZCZ CSCs (6.01%) without bending. Additionally, the PCE value of ZCA35Z CSCs showed a 9% improvement over ZCZ CSCs at a bending diameter of 10 mm. Remarkably, even after 1000 bending cycles, the PCE value of ZCA35Z CSCs exhibited a substantial 15% enhancement compared to ZCZ CSCs, which can be attributed to the continuous Cu films enhancing carrier migration and reducing optical losses. This new method to enhance the mechanical endurance of ZCZ films and ZCZ CSCs by increasing Cu film continuity via Cu–Ag co-sputtering presents a promising approach to boost the performance of flexible electronics. [Display omitted] • ZCZ films' optical and electrical properties were enhanced by improving Cu film continuity. • The average transmittance of ZCAZ films is up to 89.05%. • The films show an ultra-low resistivity of 1.19 × 10-4 Ω cm at 35W Ag power. • PCE of ZCA35Z CSCs was improved by 15% compared to ZCZ CSCs with 1000 bending cycles. • ZCAZ film enabling flexible CZTS solar cells with desirable mechanical endurance. [ABSTRACT FROM AUTHOR]

Compared with typical mono-facial photovoltaic (PV) solar modules, bifacial solar modules can make full use of reflected or scattered light from the ground and the surroundings to yield more electrical energy. The electrical energy on the rear side depends on multiple factors, such as the IV parameters of modules, packaging materials, and installation circumstances. In this work, the power generation output is simulated and researched using the PV-SYST software program, based on the different electrical parameters of bifacial solar modules and the installation conditions of the given PV systems. The influencing factors that affect the electrical energy are further analyzed using power-loss diagrams. The results show that improving the surface albedo can raise additional energy by 8.3%, thus behaving significantly better than the mono-facial module. Furthermore, improving the siting height and incidence angle modifier (IAM) of the modules can increase the additional energy by 3.1%. In contrast, adjusting the output current or voltage of the modules adds some energy, while the modules are of the same nominal power value. It was observed that the energy level of a photovoltaic system mainly depends on the installation circumstances, but the electrical parameters of the modules themselves contribute little. [ABSTRACT FROM AUTHOR]

In recent years, polycrystalline passivated emitter and rear cell (PERC) solar cells have developed rapidly, but less research has been conducted on the preparation process of their rear side passivation layers on standard solar cell production lines. In this work, a Al2O3/SiNx rear side stacked passivation layer for polycrystalline PERC solar cells was prepared using the plasma- enhanced chemical vapor deposition (PECVD) method. The effects of different Al2O3 layer thicknesses (6.8~25.6 nm), SiNx layer thicknesses (65~150 nm) and SiNx refractive indices (2.0~2.2) on the passivation effect and electrical performance were systematically investigated, which were adjusted by TMA flow rate, conveyor belt speed and the flow ratio of SiH4 and NH3, respectively. In addition, external quantum efficiency (EQE) and elevated temperature-induced degradation experiments were also carried out to check the cell performance. The results showed that the best passivation effect was achieved at 10.8 nm Al2O3 layer, 120 nm SiNx layer and 2.2 SiNx layer refractive index. Under the optimal conditions mentioned above, the highest efficiency was 19.20%, corresponding Voc was 647 mV, Isc was 9.21 A and FF was 79.18%. Meanwhile, when the refraction index was 2.2, the EQE of the cell in the long-wavelength band (800–1000 nm) was improved. Moreover, the decrease in conversion efficiency after 45 h LeTID was around 0.55% under the different refraction indices. The above results can provide a reference for the industrial production of polycrystalline PERC solar cells. [ABSTRACT FROM AUTHOR]

In this paper, high-performance CuSCN/Si heterojunction near-infrared photodetectors were successfully prepared using nanoscale light-trapping optical structures. Various light-trapping structures of ortho-pyramids, inverted pyramids and silicon nanowires were prepared on silicon substrates. Then, CuSCN films were spin-coated on silicon substrates with high crystalline properties for the assembly of CuSCN/Si photodetectors. Their reflectance spectra and interfacial passivation properties were characterized, demonstrating their superiority of light-trapping structures in high light response. Under the irradiation of 980 nm near-infrared light, a maximum responsivity of 2.88 A W−1 at −4 V bias and a specific detectivity of 5.427 × 1010 Jones were obtained in the CuSCN/Si heterojunction photodetectors prepared on planner silicon due to 3.6 eV band gap of CuSCN. The substrates of the light-trapping structure were then applied to the CuSCN/Si heterojunction photodetectors. A maximum responsivity of 10.16 A W−1 and a maximum specific detectivity of 1.001 × 1011 Jones were achieved under the 980 nm near-infrared light irradiation and −4 V bias, demonstrating the advanced performance of CuSCN/Si heterojunction photodetectors with micro-nano light-trapping substrates in the field of near-infrared photodetection compared to other silicon-based photodetectors. [ABSTRACT FROM AUTHOR]

• ABA modification increased the optical band gap of NiO x from 3.65 eV to 3.71 eV. • The grain size of perovskite on ABA modified NiO x increased by over 28%. • The efficiency of the PSCs was enhanced to 19.1% via the modified NiO x. • After 6 days, the unpackaged PSCs decay to about 70 % of pristine efficiency. The quality of the interface between the nickel oxide (NiO x) and the perovskite contact is essential to the efficiency and stability of the device. How to effectively suppress the reaction at the interface between NiO x and perovskite is the key to improve the interface quality. Herein, a simple and scalable interface enhancement strategy for building efficient and stable perovskite solar cells (PSCs) using 4-aminobenzoic acid (ABA) molecules to modify the sputtered NiO x surface as the hole transport layers (HTLs). Meanwhile, ABA molecules not only reduce the defect density and improve the quality of perovskite films (PVK), but also improve the carrier extraction ability of NiO x and reduce interfacial non-radiative recombination. Eventually, the optimized inverted device efficiency is increased to 19.1%, and the device stability is significantly improved under unencapsulated atmospheric conditions. This provides a reference for the commercial development of PSCs. [ABSTRACT FROM AUTHOR]

Recently, the macroporous and free-shaped reduced graphene oxide paper (MFGP) has been considered a sensing medium due to its ultralightweight, flexibility and good electrical conductivity performance. Here, a highly sensitive MFGP-based strain and pressure sensor is fabricated based on the macroporous reduced graphene oxide (rGO) paper. The honeycomb-like macroporous structure was obtained using a confined space to constrain the expansion paper to a certain thickness. Due to the interlock and layer-by-layer macroporous structure, the strain and pressure sensor has an ultrahigh gauge factor of 143 in the strain range of 7.6–11% and 1.5 kPa–1 in the pressure range of 0–60 kPa. Moreover, the MFGP-based strain and pressure sensor can monitor human motions such as wrist pulse, speaking and tiny muscle movements with a very low operating voltage of 5 mV. Therefore, the high sensitivity, flexibility, low operating voltage and free-shaped of the MFGP-based strain and pressure sensors demonstrate potential applications as wearable devices. [ABSTRACT FROM AUTHOR]

The preparation of graphene films on dielectrics has great significance in the scientific and microelectronic industry, which was usually realized by a transferring process. However, the non-residue transfer of graphene films is still challenging, which hinders the practical application of graphene. Here, by utilizing direct bonding copper (DBC) ceramic plates, a face-to-face method was developed to realize the direct preparation of graphene films on dielectric substrates. By utilizing DBC ceramic plate face down to the substrate, graphene film could be first synthesized on the DBC film. The copper on the ceramic plate would melt away at elevated temperature, and the graphene film would directly attach to the target substrate. The one-step preparation process is simple and fast. On the other hand, centimeter-sized graphene films with high cleanness could be prepared by the face-to-face method. The prepared graphene film showed a mobility of ~ 6400 cm2·V−1·S−1. We believe this method would bring a new solution for the synthesis of graphene films on dielectric substrates. [ABSTRACT FROM AUTHOR]

NiOx is an ideal replacement material for organic hole transport layers, due to its chemical stability and low cost. However, the inherent insulating properties of NiOx films and the post-processing process of solution preparation have been limiting their application and development. Herein, high-quality AlyNi1-yOx hole transport layers were prepared by magnetron sputtering at room temperature without further processing. Simulation and experimental results showed that Al atoms enhance the concentration of holes in NiOx films, thus improving the electrical conductivity. In addition, the AlyNi1-yOx films exhibited match band alignment with perovskite films, enabling the improved charge transfer and exaction. Furthermore, the perovskite film quality was improved by the AlyNi1-yOx passivation. These factors resulted in an improvement in the power conversion efficiency of 5.4%, compared with undoped NiOx-based perovskite solar cells. This work provides a prospective reference for the high-throughput production of perovskite solar cells. [ABSTRACT FROM AUTHOR]

Summary: In recent years, the laser half‐cutting technology for silicon solar cells has gotten much attention from researchers for increasing module power and would become particularly important in the photovoltaic modules domain. Herein, this paper would introduce a kind of new laser cutting process, a thermal laser separation (TLS) cutting technology. In the laser cutting processes, the influence on mechanical and electrical characteristics of bifacial p‐type passivated emitter and rear (PERC) solar cell and module were investigated in considerable detail. We have made a series of research and analyses including the cutting principle, opening length, fracture surface, and hot influence zone. The results reveal that the TLS cutting process could reduce damage more than the regular laser scribing and cleaving (LSC) cutting process. The TLS cutting process would achieve the higher power of a PERC half‐cutting bifacial module and the stronger bending strength of half solar cells than the LSC cutting process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-powered MoS 2 /Si flexible photodetectors with Al 2 O 3 interface were developed. • The vertical MoS 2 nanofilms were grown by RF magnetron sputtering and Al 2 O 3 by ALD. • The photodetectors could be bent up to 120° and worked well after 200 bending times. • R of 0.047 A/W and D* of 5.67 × 1011 Jones were obtained under 980 nm with 200 μW/cm2. The self-driven flexible photodetector is vitally important for next-generation optoelectronics. Two-dimensional (2D) molybdenum sulfide (MoS 2) as a typical family member of transition-metal dichalcogenides (TMDs) has shown larger potential applications in the high-sensitivity photodetection due to its self-physical properties. Herein, the ultrafast MoS 2 /Si flexible photodetector with ultrathin Al 2 O 3 passivation interface and high light-trapping structures was fabricated. The MoS 2 /Al 2 O 3 /Si flexible photodetector exhibits excellent performance with a high responsivity of 0.047 A/W, detectivity up to 5.67 × 1011 Jones and rise/fall time of 25.6/3.2 μs. Furthermore, this optoelectronic device can withstand bending angles of 120° and work well after 500 bending times. This unique performance can be attributed to the flexible Si substrate with good mechanical properties, high-light trapping structures and an Al 2 O 3 passivation interface. This device can find potential applications in e-skins, flexible displays and smart health care. [ABSTRACT FROM AUTHOR]

Designing and preparing lightweight electromagnetic shielding materials at the micron level is crucial for aerospace and military applications. Vertical graphene nanowalls (VGNs) offer high efficiency for electromagnetic shielding due to attributes such as high carrier mobility, porosity, and low density. This study presents the preparation of ultra-thin VGNs/metal stacked films via plasma-enhanced chemical vapor deposition (PECVD) for VGNs, and combined electron beam evaporation (EBE) with cyclic PECVD for metal layers. The PECVD technique ensures homogeneity and controllable thickness of the VGNs. The experimental results demonstrate that the interface between the VGNs and the metal layer exhibits good interfacial contact, resulting in high carrier mobility. Furthermore, incorporating a metal layer with a thickness ratio of 10 % significantly enhances conductivity by an order of magnitude. The hybrid structures exhibit remarkable electromagnetic shielding effectiveness per unit thickness (∼5300 dB mm−1) evaluated in the X-band range (8–12 GHz). Stacked films as thin as 0.01 mm achieve up to 53.4 dB of electromagnetic shielding. Finite element simulations indicate that the presence of opposing electric fields at the graphene-metal interface contributes to higher ohmic loss. The coupling effect at the interface significantly contributes to the material's excellent electromagnetic shielding effectiveness. [Display omitted] • Ultrathin VGN/metal stacked structures were prepared by alternating EBE/PEVCD. • The addition of a metal layer greatly improved the conductivity of the structure. • The VGN/metal stacks exhibited 53.4 dB of EMI shielding efficiency in the X-band. • The EMI shielding efficiency per unit thickness of the stacks reached 5340 dB·mm−1. [ABSTRACT FROM AUTHOR]

Tin-based nanocomposite materials embedded in carbon frameworks can be used as effective negative electrode materials for lithium-ion batteries (LIBs), owing to their high theoretical capacities with stable cycle performance. In this work, a low-cost and productive facile hydrothermal method was employed for the preparation of a Sn/C nanocomposite, in which Sn particles (sized in nanometers) were uniformly dispersed in the conductive carbon matrix. The as-prepared Sn/C nanocomposite displayed a considerable reversible capacity of 877 mAhg−1 at 0.1 Ag−1 with a high first cycle charge/discharge coulombic efficiency of about 77%, and showed 668 mAh/g even at a relatively high current density of 0.5 Ag−1 after 100 cycles. Furthermore, excellent rate capability performance was achieved for 806, 697, 630, 516, and 354 mAhg−1 at current densities 0.1, 0.25, 0.5, 0.75, and 1 Ag−1, respectively. This outstanding and significantly improved electrochemical performance is attributed to the good distribution of Sn nanoparticles in the carbon framework, which helped to produce Sn/C nanocomposite next-generation negative electrodes for lithium-ion storage. [ABSTRACT FROM AUTHOR]

In this work, fast response and broadband self-powered photodetectors based on heterojunctions of vertical smooth silicon nanowires (SiNWs) were proposed, which were achieved through spin-coating p-CZTS on top of n-SiNWs adopting a simple two-step method. First, CZTS was uniformly and tightly attached to the sidewalls of SiNWs in the form of nanoparticles. The prepared CZTS/SiNWs core-shell heterojunctions exhibited typical rectification characteristics in dark and excellent light response characteristics in light illumination. Our device could perform self-driven detection under the UV-VIS-NIR light irradiation without an external energy supply. The responsivity and specific detectivity were estimated to be 14 mAW-1 and 1.5 × 1011 Jones, which can be improved to 0.35 AW-1 and 1.2 × 1013 Jones at −1.5 V bias. In addition, the present device also possesses distinct advantages of a large I light /I dark ratio exceeding 4.25 × 104, fast response rate with rise/fall times of 1.4/14.2 μs, and outstanding environmental stability. Finally, a heart rate health monitoring application by CZTS/SiNWs detector was proposed. All these results may pave a way for the real application of the self-driven detector in the field of health monitoring in the future. [ABSTRACT FROM AUTHOR]

Tin oxide (SnO2) and tin-based composites along with carbon have attracted significant interest as negative electrodes for lithium-ion batteries (LIBs). However, tin-based composite electrodes have some critical drawbacks, such as high volume expansion, low capacity at high current density due to low ionic conductivity, and poor cycle stability. Moreover, complex preparation methods and high-cost carbon coating procedures are considered main challenges in the commercialization of tin-based electrodes for LIBs. In this study, we prepared a Sn/SnO2/C nano-composite structure by employing a low-cost hydrothermal method, where Sn nanoparticles were oxidized in glucose and carboxymethyl cellulose CMC was introduced into the solution. Scanning electron microscope (SEM) and transmission electron microscope revealed the irregular structure of Sn nanoparticles and SnO2 phases in the conductive carbon matrix. The as-prepared Sn/SnO2/C nano-composite showed high first-cycle reversible discharge capacity (2248 mAhg−1) at 100 mAg−1 with a first coulombic efficiency of 70%, and also displayed 474.64 mAhg−1 at the relatively high current density of about 500 mAg−1 after 100 cycles. A low-cost Sn/SnO2/C nano-composite with significant electrochemical performance could be the next generation of high-performance negative electrodes for LIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Random inverted pyramid textured PDMS films are prepared by a simple process. • They are used as radiative cooling emitters for heat dissipation of solar cells. • The transparency and cooling power are both improved by the texturing treatment. • A temperature drop of 17 ℃ and an efficiency rise of 1.02% of the cells are shown. • Surface texturing treatment also improves the hydrophobicity of PDMS films. Radiative cooling is a promising passive cooling phenomenon. For the heat dissipation of silicon solar cells, radiative cooling emitters require high transmittance in the wavelength range of 300–1100 nm and high emissivity in the range of 8–13 μm. In this paper, a simple and low-cost coating and embossing process is proposed to texture the surface morphology of the PDMS film. A radiative cooling emitter is prepared with a random inverted pyramid-like light-trapping structure on the surface. The experimental results show that the transparency and radiative cooling performance of textured polydimethylsiloxane films are improved by 2.1% and 2.7%, respectively. When using a polished Al mirror as the substrate, the radiative cooling temperature difference and net radiative cooling power are increased to 12.8 ℃ and 103 W·m−2, respectively. By employing it as a solar cell radiator, the radiative heat dissipation power of the solar cell is increased by 67 W·m−2, and the working temperature is reduced by over 17 ℃. An improvement in photoelectric conversion efficiency of 1.02% is achieved. It is demonstrated that the texturing treatment also improves the hydrophobicity of the polydimethylsiloxane film. The film is more applicable for radiative cooling emitters that are directly exposed to the atmosphere in outdoor environments. [ABSTRACT FROM AUTHOR]

In this work, ZnO/Ag(Cu doped)/ZnO and ZnO/(Cu doped) Ag/ZnO/SiO2 multilayer films are prepared on glass by a sputtering technique. The optical, structural, and morphological properties of the Ag-based multilayer structures are compared. According to the results of the transmittance curve, it is found that the Cu doping into Ag leads to a significant broadening of the transmittance spectrum of the multilayer. The performance of the multilayer largely depends on the deposition time of different films. After doping with copper, the average light transmittance of the multilayer film exceeds 81.2% from 380 to 1100 nm, and the average light transmittance exceeds 10.2% from 1100 to 2500 nm. When the SiO2 anti-reflection layers are introduced, the average light transmittance of the multilayer structure from 380 to 1100 nm exceeds 85.2%, and this value reaches 18.3% from 1100 to 2500 nm. In addition, a 6-inch ZnO/Ag(Cu doped)/ZnO/SiO2 multilayer is used as the cover layer of the silicon solar cell. After 2 h of sunlight exposure, the increase in working temperature is reduced by 12 °C while the open-circuit voltage reduction is reduced by 4.1% in comparison with that using standard glass. [ABSTRACT FROM AUTHOR]

Cu 2 ZnSnS 4 (CZTS) solar cells occupy an important direction in the field of clean energy research due to their environmental friendliness, low cost, and industrial technology compatibility. The complex and variable usage environment also accelerates the development of flexible CZTS solar cells. However, the inferior flexibility of ITO films limited their development. ZnO/Ag/ZnO (ZAZ) films are potential choices for transparent conductive layers of CZTS solar cells due to their high transmittance, conductivity, and flexibility. To further enhance the photovoltaic performance and mechanical durability of ZAZ films and solar cells, Ag 2 O was introduced into ZAZ film by magnetron sputtering. An ultra-high average transmittance of 96.6% in 400–800 nm was achieved for ZnO/Ag-Ag 2 O/ZnO (ZAAZ) films at Ag 2 O sputtering power of 40 W, which was attributed to the fact that Ag 2 O effectively inhibited the growth of 3D islands of Ag film, and formed a more uniform Ag film. ZAAZ films offered a superior figure of merit value of 0.1041 Ω−1. The power conversion efficiency (PCE) of ZAAZ solar cells was 6.94%, higher than that of ZAZ solar cells (6.69%). Remarkably, the PCE of ZAAZ solar cells was 7.9% higher than that of ZAZ solar cells after 1000 bending cycles. Therefore, Therefore, this approach may provide a promising way to improve the photovoltaic performance and mechanical durability of flexible solar cells. • Ag 2 O was co-sputtered to increase Ag film continuity in ZnO/Ag/ZnO film. • A transmittance of 96.6% in ZnO/Ag-Ag 2 O/ZnO film was achieved by using Ag 2 O. • The ZAAZ film showed an ultra-low sheet resistance of 6.8 Ω·sq−1 at 40 W Ag 2 O power. • The power conversion efficiency of ZAAZ CSC was 0.25% higher than that of ZAZ CSC. • The Ag 2 O could also improve the mechanical durability of flexible ZAAZ CSC devices. [ABSTRACT FROM AUTHOR]

Ag has been incorporated into the CZTS film through post-doping by magnetron sputtering to decrease the Cu Zn anti-site defect. Efforts have been dedicated to optimize the Ag sputtering time and 60 s will be the best as surveyed from the SEM, XRD and Raman spectra. Then the broad-band self-driven heterostructure photodetector has been manufactured by combining the CZTS and inverted pyramid n-Si (IP n-Si). The device represents the first-rank property under the irradiation of 5 mW, 780 nm LED with 0 V bias with the responsivity and detectivity of 7.2 mA/W and 4.98 × 1010 Jones respectively. The device can persist excellent linearity when enduring a 40 mW-80 mW, 980 nm NIR laser with 0 V bias. The comprehensive performance becomes the best under the irradiation of a 50 mW laser. The responsivity and detectivity are 1.22 mA/W and 1.98 × 1010 Jones. The device can also work stably as the laser changes from 1 Hz to 15 kHz. The rise time and decay time are 93.3 μs and 141.0 μs respectively. These results open up an innovative application for CZTS to build a broad-band self-driven photodetector as a window-layer. Then we irradiate the device with a 980 nm infrared laser, the bias voltage is still 0 v, but the power of the irradiation is changed from 40 w to 80 w to study the stability of the device under different light intensities, and whether it can maintain good linear characteristics. [ABSTRACT FROM AUTHOR]

• An air-stable hybrid-structure solar selective absorber (hs-SSA) was made on Si. • The ultra-thin textured Si (ut-Si) showed excellent flexibility and absorptivity. • The hs-SSA performed good thermal stability in the air and vacuum. • The Δα/α and Δε/ε were only 0.31% and 1.18% for air-annealing at 250 °C for 120 h. • Its α/ε keet at 0.962/0.352 after annealing at 500 °C in a vacuum for 72 h. A kind of air-stable hybrid-structured solar selective absorber (hs-SSA) with enhanced thermal stability is prepared by combining ultra-thin textured silicon (ut-Si) with cermet coating. The ut-Si obtained by the wafer thinning and fast texturization method shows excellent flexibility and light-trapping ability. Then the W-WO x coatings are deposited onto the ut-Si substrate in a spreading manner on the pyramid-like structure. The as-deposited hs-SSA exhibits good light-harvesting capability with spectral selectivity (α/ε) of 0.968/0.340. Additionally, the ut-Si shows its superiority in oxidation resistance and chemical stability compared with the traditional metal substrate. After 120-h air-annealing at 250 °C and 72-h vacuum-annealing at 500 °C, the performance losses are within a tiny and reasonable range, showing excellent chemical, structural and optical stability, exhibiting excellent application potential in medium-temperature solar harvesting field. [ABSTRACT FROM AUTHOR]

Double-layer films of ZnO and antimony doped tin oxide (ATO) have great potential for application in photoelectric devices by the integration of the ultraviolet (UV) absorbance of the ZnO layer and the near-infrared (NIR) blocking and conductivity induced by the ATO film. Thus the nanostructure of ATO film on the surface of the ZnO layer plays an important role in determining the photoelectric property of ZnO/ATO bilayer film. In this work, ATO films are deposited on the ZnO layer by a radio frequency magnetron sputtering method and the structures and photoelectric properties, particularly the electric properties of ATO films on the ZnO layer are investigated by the regulation of gas flow ratio of O2/Ar and the sputtering power. After optimization of the conditions depositing ATO films on the ZnO layer, which is at an O2/Ar ratio of 2:13 with sputtering power of 150 W, ATO film shows a good conductivity of about 213.4 Scm−1 after annealing in nitrogen at 500 °C for 1 h. The double-layer film of 500 nm ATO film on 200 nm thick ZnO layer presents good optical properties with a high UV-blocking of 96% (280–380 nm), a NIR-blocking of 80% (1100–2500 nm) and light transmission of about 70% (380–1100 nm). [ABSTRACT FROM AUTHOR]

A novel nanomaterial formed by a Cu2ZnSnS4 (CZTS)/CeO2 heterojunction with excellent electrochemical sensing for ammonia nitrogen was prepared by a microwave irradiation method combined with a hydrothermal method. The properties of the CZTS/CeO2 heterojunction were investigated by a series of characterizations such as Raman spectra, x-ray diffraction, scanning electron microscopy, thermogravimetric analysis, specific surface area (SSA), temperature-programmed desorption of ammonia and UV–vis spectroscopy. Nickel foam was used as a conductive frame electrode in order to enhance the sensitivity of the sensor along with the electrical conductivity, permeability and SSA. It is revealed by electrochemical measurements that the ammonia nitrogen oxidation reaction occurring in the sensing electrode of the CZTS/CeO2 heterojunction demonstrated regulation of Ip (mA) = 6.4 × 10−3C (mM)+ 0.1527 (R2= 0.9987) in a wide concentration range of 0–380.0 mM with a low detection of 6.0 μM according to the signal-to-noise ratio (S/N= 2). The CZTS/CeO2 heterojunction is expected to become a new candidate semiconductor nanomaterial for the electrochemical detection of ammonia nitrogen in an aqueous solution. [ABSTRACT FROM AUTHOR]

• Thickness of the boron rich layer of the boron emitter was reduced by using SiO 2 nanosphere assisted diffusion process. • Boron rich layer could be removed completely with little effect on minority carrier lifetime. • Achieved a maximum cell efficiency of 20.26% and the efficiency was enhanced by 0.54% In this paper, spin-on doping (SOD) process using commercial boron dopant source was applied to form front p-type emitter on n-type mono-crystalline CZ substrate. Results showed that the thickness of boron rich layer (BRL) decreased from 180 nm to 20 nm with SiO 2 nanosphere assisted SOD and the BRL can be removed entirely by further in-situ oxidation. Furthermore, the hole concentration of the emitter reduced from 5.5 × 1019 cm3 to 2.8 × 1019 cm3 by integrating these two processes. In a symmetric sample without BRL, a very low emitter saturation current density of 32 fA/cm2 with implied-Voc over 700 mV was obtained. The minority carrier lifetime got improved more than 30% after diffusion. Finally, n-PERT solar cell with a conversion efficiency of 20.26% was achieved using optimized boron emitter, showing an enhanced conversion efficiency of 0.54%. [ABSTRACT FROM AUTHOR]

Sn precursor layer was evaporated on a glass substrate by an electron-beam evaporation method and followed by selenization using Se powder. SnSe film was successfully prepared by adjusting the selenization temperature and selenization time. The phase, microstructure and optical properties of the SnSe films were studied by X-ray diffraction, Raman spectroscopy, Scanning Electron Microscopy, and UV-Vis-NIR spectrophotometer. The results demonstrated that the pure phase polycrystalline SnSe films with a band gap of 0.93 eV could be prepared by selenizing at 450 ∘ C for 60 min. Under the irradiation of a 980 nm laser with a power of 2 mW/cm2, photoelectric response characteristics of the SnSe films were tested, and the response time and recovery time of the prepared film were 62 ms and 80 ms, respectively, indicating that the SnSe film had a large application prospect in near-infrared light detection. [ABSTRACT FROM AUTHOR]

• A light-trapping nano honeycomb structure was prepared on a c-Si wafer surface. • The honeycomb structure showed excellent reflectance and passivation. • An efficiency of 22.80% was achieved in PERC cell with honeycomb structure. • Efficiency gain of 0.3% was obtained compared with normal upward pyramid texture. In this paper, a light-trapping nano honeycomb (NH) structure with a polyhedral interior was prepared on a c-Si wafer surface, which has a much lower reflectance and better passivation effect than that of a pyramid-textured surface. The NH structure was prepared using the metal-assisted chemical etching method together with the nanostructure rebuilding (NSR) method. Through reflectance measurement, internal quantum efficiency characterization and finite-difference time-domain simulation, the advantages of the NH structure were systematically studied. The formation mechanism of the NH structure was considered to be due to both the anisotropic and isotropic etching properties of Si crystal, and its main affecting factor was the NSR reaction time. To further demonstrate its potential in monocrystalline silicon cells, passivated emitter and rear cells (PERC) using NH-textured c-Si wafers were fabricated. A high efficiency of 22.80% was achieved, which was 0.3% and 0.16% higher compared to the normal upward pyramid-textured PERC and the inverted pyramid-textured PERC, respectively. The NH structure is expected to have a great potential application in the mass production of c-Si solar cells. [ABSTRACT FROM AUTHOR]

The most effective and potential approach to improve the performance of heterojunction photodetectors is to obtain favorable interfacial passivation by adding an insertion layer. In this paper, MoOx/Al2O3/n-Si heterojunction photodetectors with excellent photocurrents, responsivity and detectivity were fabricated, in which alumina acts as a tunneling passivation layer. By optimizing the post-annealing treatment temperature of the MoOx and the thickness of the ultra-thin Al2O3, the photodetector achieved a ratio of photocurrent to dark current of 3.1 × 105, a photoresponsivity of 7.11 A W−1 (@980 nm) and a detective of 9.85 × 1012 Jones at −5 V bias. Besides, a self-driven response of 0.17 A W−1 and a high photocurrent/dark current ratio of 2.07 × 104 were obtained. The result demonstrated that optimizing the interface of heterojunctions is a promising way to obtain a heterojunction photodetector with high-performance. [ABSTRACT FROM AUTHOR]

• SiO 2 nanospheres were used for more uniform phosphorus diffusion. • An enhancement of minority carrier lifetime from 42 μs to 56 μs was obtained. • A small square resistance of 22 Ω/sq was made at high phosphoric acid concentration. • The efficiency in the cell center was enhanced by 40.54% using the nanospheres. In order to improve the quality of n+ emitter fabricated by phosphorus doping, SiO 2 nanospheres were added into a phosphoric acid solution for spin-on doping. Through a complete analysis of the trade-off between the diffusion uniformity and sheet resistance, the particle size of SiO 2 nanospheres is selected to be 230 nm. It is found that with the increase of phosphoric acid concentration from 50% to 85%, the average sheet resistance decreases from 128.5 Ω/sq to 18.1 Ω/sq, and the diffusion uniformity increased from 95.2% to 98.5%. In a large concentration range, the surface doping concentration of the emitter will increase with phosphoric acid, but when the concentration of phosphoric acid reaches 80%, the surface doping concentration will be almost unchanged. Nevertheless, different from above, the p-n junction depth has little dependence on the phosphoric acid concentration. Moreover, the efficiencies in the solar cell center and edge are enhanced by 40.54% and 88.08% respectively using SiO 2 nanospheres assisted diffusion. [ABSTRACT FROM AUTHOR]

Summary: In this paper, we investigate the influence of silicon oxide (SiOx) layer on the potential induced degradation (PID) of P‐type monocrystalline PERC cells and modules. A SiOx layer was added between the aluminum oxide (AlOx) and silicon nitride (SiNx) layers on the rear side of PERC cells using a newly designed plasma enhanced chemical vapor deposition (PECVD) tool, MAiA from Meyer Burger. The performance of cells and modules with this AlOx + SiOx + SiNx stack was characterized by electrical breakdown (EBD), cell degradation indicator (CDi) and climate chamber PID tests. The EBD test results indicate that the AlOx + SiOx + SiNx stack has higher breakdown voltage than the typically used AlOx + SiNx stack. After undergoing CDi tests, power degradation is more severe in PERC cells with AlOx + SiNx passivation stack than those with AlOx + SiOx + SiNx passivation stack, as evidenced by darker photoluminescence. Bifacial modules made from PERC cells with the AlOx + SiOx + SiNx rear passivation stack demonstrate a significant reduction in rear PID from 12.3% to 4.2%. The results above depict that the addition of a SiOx layer between the AlOx and SiNx layers could effectively reduce the transfer of positive charges from the SiNx layer into the AlOx layer. [ABSTRACT FROM AUTHOR]

Various gas sensors have made considerable improvements to the quality of people's lives. However, in most cases, changing of materials is necessary to adapt to the changing of the target gas, which limits the further application of gas sensors. To meet this challenge, in this work, molecular imprinting (MI) technology is introduced. Acrylic acid is used as a functional monomer, while gas molecules, including acetone, are used as templates. The MI process with an acetone template helps improve the acetone selectivity of TiO2 by up to 1.74–2.80 times. Moreover, it proved that other templates can increase the corresponding selectivity by at least 1.5 times by using the same matrix material. These results demonstrate the potential importance of the MI process in constructing a highly compatible gas sensor industry. Beyond this, the MI process has proved to achieve an ultrahigh specific surface area of 384.36 m2 · g−1. The optimal acetone sensor exhibits desirable comprehensive performance compared with other reports. An excellent TiO2 based prototype acetone sensor working at 300 °C with a low detection limit of 18 ppb is obtained. [ABSTRACT FROM AUTHOR]

The solution based on dimethylformamide (DMF) has shown promising application prospects in the fabrication of high-efficiency Cu 2 ZnSnS 4 solar cells. However, due to the high boiling temperature of the solvent, it is difficult to completely volatilize DMF during the evaporation process after spin coating, leading to remains of C and O atoms at grain boundaries, which severely restricts the photoelectric performance of solar cells. In this study, ethyl acetate (EA) with green character was used as an additive to optimize the film formation process of DMF-based CZTS precursor. The experimental results showed that using a small amount of EA additives could effectively improve morphology, crystallinity, composition distribution and electrical properties of the CZTS absorber. In addition, the CZTS and CdS heterojunctions exhibited a cliff-like energy band structure, and the optimized conduction band offset increased the activation energy required for the carrier recombination path, consequently reducing the carrier recombination. Compared with the pure DMF precursor solution, the photoelectric conversion efficiency of CZTS solar cells with an EA addition ratio of 10% was improved by 42%, and the open circuit voltage of the device reached 601 mV. [ABSTRACT FROM AUTHOR]

A series of Pr3+ doped SrWO 4 phosphors were synthesized using solid-state reaction routes. The phase composition, photoluminescence and temperature sensitivities of as-prepared materials were investigated. Rietveld refinement of measured XRD data was applied to analyze the lattice parameters. The optical transition was elaborated using UV–visible diffuse reflectance spectra and photoluminescence spectra. The photoluminescence measurements confirmed the strong visible light emission from the developed phosphors under both UV excitation at 250 nm and blue excitation at 450 nm. Notably, the maximum emission intensity was observed at a Pr3+ doping concentration of 2 mol%. Furthermore, the fluorescence intensity ratio (FIR) technique was employed, focusing on the emissions originating from the 3P 0 and 1D 2 state of Pr3+ within the temperature range of 298–598 K. Two FIR groups were adopted in this case, which can verify each other to achieve self-calibration. Typically, SrWO 4 :0.02Pr3+ exhibited remarkable performance as a temperature sensor, displaying an absolute sensitivity (Sa) of 3.11%K−1 and a relative sensitivity (Sr) of 0.81%K−1. As a result, the significant temperature-dependent PL and remarkable down-conversion luminescence make the SrWO 4 :Pr3+ material a promising candidate for optical thermometers and UV to visible converters of solar cell applications. • Intense visible emission of SrWO 4 :Pr3+ excited by 250 nm and 450 nm was observed. • FIR from non-thermally coupled energy levels was used for temperature sensing. • The wide-range and highly-sensitive of optical temperature sensing were realized. • The self-calibration of temperature measurement was achieved by two FIR groups. [ABSTRACT FROM AUTHOR]

• Doped poly-Si/SiO x passivation was used for front side of p-type PERC cell. • Obvious passivation effect was obtained in the PERC cells with the poly-Si/SiO x. • Dark recombination current density was reduced to about 3 fA/cm2 in test sample. • An enhanced V oc value of 10 mV was achieved in the passivated p-type PERC cell. The most promising and feasible approach to achieving high-efficiency silicon solar cells must be passivation contact compatible with current homojunction thermal processes. In this paper, an easy-to-implement carrier-selective passivation contact with doped poly-Si/SiO x for produing p-type passivated emitter and rear cell (PERC) was proposed. The passivation contact structure consisted of an ultra-thin SiO x layer capped with an intrinsic amorphous silicon (a-Si) layer prepared by low pressure chemical vapor deposition, which was deposited onto a p-type silicon substrate and then was doped and re-crystallized by a thermal phosphorus diffusion at 850 °C for 75 min. By optimizing the diffusion profile and cleaning time, a low dark recombination current density J 0 ≈ 3 fA/cm2 and large minority carrier lifetime of 3000 μs were achieved on the 180-μm-thick n-type wafers with a resistivity of 3 Ω·cm, corresponding to an implied open-circuit voltage of 700 mV. P-type PERC cells with the highly doped poly-Si/SiO x passivated emitter demonstrated 683.97 mV of open-circuit voltage, showing more than 10 mV enhancement comparing with regular PERC cells. The results demonstrated an attractive potential of the carrier-selective passivation contacts with doped poly-Si/SiO x under front metallizatin area in photovoltaic application. [ABSTRACT FROM AUTHOR]

The application of TiO2 acetone monitor is highly limited by the high operating temperature and poor sensitivity. In this work, black TiO2 (B-TiO2) is produced by Ti3+ self-doping and is followed by Ag modification to form B-TiO2@Ag. It is first demonstrated that the operating temperature and sensitivity of TiO2 to acetone can be promoted evidently. By introducing a Ti3+ self-doped layer on the surface of TiO2, as observed in TEM images, the band gap of TiO2 is reduced to 3.01 eV. Ag surface decoration is carried out for the enhancement of electron generation. Optical absorption and the Hall effect results prove that B-TiO2@Ag exhibits highest photoelectrical properties. As a result, the B-TiO2@Ag gas sensor with a low operating temperature at 250 °C and high response of 68.19 to 50 ppm acetone is realized. The low detection limit of B-TiO2@Ag sensor reaches 887 ppb, which provides an applicable way for non-invasive detection of blood glucose. [ABSTRACT FROM AUTHOR]

The troublesome residual stress is always a stumbling block that drags the progress pace of flexible CZTSSe thin film solar cells, which urgently needs to be noticed and solved. In this paper, low-temperature prepared CZTSSe absorber with relieved residual stress (0.558 GPa) is realized by Sb incorporation. Owing to the evaporated 20 nm Sb layer under CZTS precursor, the crystalline quality and band mismatching of CZTSSe/CdS interface are simultaneously improved. Additionally, the spatial potential fluctuation extracted from the PL results is found to decrease from 63.26 meV to 41.57 meV, indicating a reduction in band tailing and disorder of CZTSSe absorber. Compared with the general solar cells fabricated at 580 °C, flexible devices with Sb incorporation can maintain a slightly higher performance at a lower temperature about 60 °C. The best power conversion efficiency (PCE) of 4.41% is obtained in the solar cell with 550 °C-selenized CZTSSe absorber after incorporating 20 nm Sb layer, featuring 351.20 mV Voc, 25.73 mA/cm2 Jsc and 48.79% FF. Finally, low-temperature prepared flexible CZTSSe thin film solar cell can retain over 83% of the original PCE after bending at 180° for 40 cycles. The mechanical durability paves a promising way for flexible CZTSSe thin film solar cell in roll-to-roll production. [ABSTRACT FROM AUTHOR]

In recent years, Ti3+ self-doped TiO2 (B-TiO2) exhibits great potential as a photocatalyst. In this work, Ti vapor-assisted annealing is first demonstrated for Ti3+ doping and improving the visible absorption of TiO2. TEM results exhibit the formation of disordered layer, indicating the successful fabricating of B-TiO2. The absorption increase in TiO2 caused by Ti vapor annealing reaches nearly 50% in the visible wavelength range. Benefiting from the absorption increase, the photocatalytic performance of TiO2 after Ti vapor annealing increases by 60–70%. Surface modification of Ag onto B-TiO2 is also carried out to further improve its optical property. Ag-modified Ti3+ self-doped TiO2 (B-TiO2@Ag) exhibits great visible photodegradation behavior to RhB. The RhB degradation rate reaches 97.76% after 60 min of visible light irradiation. Electrochemical performance tests demonstrate that as-prepared TiO2@Ag has lower resistance than W-TiO2. The results indicate that B-TiO2@Ag has great potential in solar photocatalytic degradation of pollutant. [ABSTRACT FROM AUTHOR]

• Evaporated Sb layer was inserted into CZTSSe precursor for the first time. • Hole concentration in CZTSSe was found to increase with Sb layer thickness. • The grain growth of CZTSSe benefited a lot from the introduced Sb layer. • The electrostatic potential fluctuation was reduced after the incorporation of Sb. • 20 nm evaporated Sb layer took effect to the fullest extent in PCE enhancement. Cu 2 ZnSn(S,Se) 4 (CZTSSe) chalcogenide with natural-abundance, environment -friendly and impressive photovoltaic performance is promising material for kesterite thin film solar cell. In this paper, the effects of evaporated Sb layer on performance of flexible CZTSSe thin film solar cell are investigated. Systematic studies show that the quasi-liquid Sb 2 Se 3 plays productive roles in promoting grain growth, subsequently volatilizes in the elevated selenization temperature without entering into the CZTSSe lattice. Obvious improvements in crystallinity, grain size, surface roughness, hole concentration and device performance are obtained after optimizing the thickness of Sb layer. The electrostatic potential fluctuation extracted from the PL results is found to decrease from 115.9 meV to 60.7 meV after introducing 20 nm evaporated Sb layer. Finally, 20 nm evaporated Sb layer takes effect to the fullest extent which shows a 69% increase in photoelectric conversion efficiency (PCE). The incorporation of Sb opens up access to opportunity in roll-to-roll process for thin film solar cells. [ABSTRACT FROM AUTHOR]

In this paper, the one-step Cu-assisted chemical etching method is reported for controllable thinning and texturization on mono-crystalline silicon in Cu2+/HF/H 2 O 2 mixture solution. HF and Cu2+ exhibited a synergetic effect on accelerating etching process while H 2 O 2 slowed down the preferential Si (100) etching by oxidizing the Cu atoms. Within optimal 0.15 M Cu2+/4 M HF/0.88 M H 2 O 2 solution, quasi-inverted pyramid-like structures of 2–4 μm in size and a reflectance of 8.46% were obtained at 20 °C. By adjusting the temperature and etching time, ultra-thin silicon wafers with thickness of 19–120 μm were fabricated. Comparing the microstructures obtained at 20 °C and 60 °C, widths and inclination angles were distinct. By illustrating the transportation and distribution of holes during the etching process, the intrinsic connection between thinning and texturization was studied. The etching results, including etching rates and morphologies, were determined by the distribution of holes between the B' and B" orbitals. In summary, controllable fabrication of textured ultra-thin silicon wafers with desired thickness and microstructures could be achieved by one-step, short-time and low-temperature Cu-assisted chemical etching method, exhibiting a great potential use in ultra-thin silicon solar cells. [ABSTRACT FROM AUTHOR]

Efficient up/down conversion (UC/DC) thin films with high transmittance were prepared by an anisole dissolved polymethyl methacrylate (PMMA) solution mixed with β-NaYF 4 : 5% Er, 10% Yb (UCNPs) and β-NaYF 4 : 10% Tb, 1% Yb (DCNPs) nanocrystals, which required no postdeposition heat treatment. The full embedment of nanoparticles in the PMMA matrix was confirmed by atomic force microscopy, and the films were dense and uniform with high transmittance. Both UCNPs and as-prepared films exhibited strong UC emission bands in the green and red region. The relative intensities of green to red emissions in the films were enhanced compared with UCNPs because of the surface passivation by PMMA. Under excitation of 355 nm laser, both DCNPs and as-prepared films exhibited down conversion luminescence and no obvious intensity difference was observed between nanoparticles and the films. By tape test, the conversion films were proved with a strong adhesion due to the protection of PMMA. The results suggested that PMMA is a good matrix for fabrication of efficient UC/DC films with high transmittance and good adhesion. • Nanosized UC and DC materials were synthesized via a modified solvothermal method. • The film with both UC and DC emissions was prepared without post heat treatment. • The transparent conversion film had a strong adhesion with the protection of PMMA. [ABSTRACT FROM AUTHOR]

In this work, we carried out a numerical study on the role of thermal capture cross sections in impurity photovoltaic (IPV) effect for silicon solar cells doped with indium. The short-circuit current density, the open-circuit voltage and the conversion efficiency of the IPV cell were calculated in dependence of variable electron and hole thermal capture cross sections of indium in silicon. We found that the thermal capture cross section of electron is crucial to the device performance and that of hole has few influence on the cell property for this IPV cell since acceptor-type indium impurity level is near the valence band edge. If the electron thermal capture cross section is less than 10-20 cm2, a positive gain of conversion efficiency for the IPV cell would be presented. We concluded that those impurities with small electron (or hole) thermal capture cross sections may be suitable for use in the IPV cell with acceptor-type (or donor-type) impurity level near the valence (or conduction) band edge. These results may help to evaluate the potential of the IPV effect for improving cell efficiency according to the thermal capture cross sections of the impurity in host semiconductor. [ABSTRACT FROM AUTHOR]

Poor flexibility of ITO films restricted the photovoltaic characteristics of flexible CZTS solar cells (SCs). In this study, ZnO/Ag/ZnO (ZAZ) transparent conductive films with high transmittance and flexibility were prepared and applied as the transparent conductive layer of flexible CZTS SCs to enhance the photovoltaic characteristics. By regulating the thickness of the Ag metal layer, ZnO/Ag9nm/ZnO (ZA9Z) provided the best photovoltaic properties: resistivity 9.16 × 10−5 Ω cm, average transmittance 95.8%, maximum transmittance of 97.4%, and figure of merit (FOM) 78.4 10−3 Ω−1. Moreover, CZTS SCs with ZA9Z film showed a power conversion efficiency (PCE) of 6.69%, almost 13% higher than those with ITO film. The PCE values of the SCs with ZA9Z film were 6.09 and 4.31 after a bending diameter of 8 mm and 1000 cyclic bending, respectively, while the ratio of PCE of the SCs with ZA9Z film to that of the SCs with ITO film was 6.88 and 12.31 under these conditions, respectively, showing that the CZTS SCs with ZA9Z film are of excellent flexibility. [Display omitted] • Photoelectric properties of CZTS SCs was enhanced by using ZAZ film instead of ITO. • The average transmittance of ZAZ films from 400 to 800 nm is up to 95.8%. • ZA9Z SCs present a PCE of 6.69% at unbending, which is almost 13% higher than ITOs. • The PCE of ZA9Z SCs is 6.08 at an 8 mm bending diameter, higher than ITO SCs of 0.88. • The PCE ratio of ZA9Z SCs to ITO SCs was 12.31 after 1000 cyclic bending. [ABSTRACT FROM AUTHOR]

Sputtered Ge layer was placed between Mo/substrate as a transition layer or between CZTSSe/Mo as a doping layer for CZTSSe/Mo/substrate. The effects of these two Ge layers on the structural, mechanical and photoelectrical properties of CZTSSe thin film and solar cells were studied. It was found that the residual stress of CZTSSe thin film decreased from −2.49 to −0.27 GPa after inserting a Ge transition layer, leading an enhancement in adhesion property. Besides, XPS analysis demonstrated that the diffusion behavior of transitional Ge into CZTSSe absorber through Mo layer during annealing process was nonexistent. The inserted Ge doping layer not only could adjust the band gap of absorber but also improve the band mismatching of CZTSSe/CdS interface. Moreover, the oxidation from Sn4+ to Sn2+ could be suppressed, which could decrease some deep defects in CZTSSe absorber. Ge transition layer and doping layer both made contributions to the increased crystalline quality. After inserting double Ge layers, a relative efficiency enhancement of 48% was achieved due to the reduced residual stress, improved crystalline quality, increased CBO and the alleviated band mismatching of CZTSSe/CdS interface. • Double Ge layers were inserted into flexible CZTSSe thin film solar cells. • The residual stress of absorber was released after inserting a Ge transition layer. • Double Ge layers can alleviate the band mismatching at the interface of CZTSSe/CdS. • The oxidation of Sn+4 to Sn+2 was suppressed after inserting a Ge doping layer. [ABSTRACT FROM AUTHOR]

In this study, a novel phase change material (PCM) of epoxy resin sealed expanded graphite/paraffin composite was developed as an independent attachment for building applications. A relatively high thermal energy storage density and a high thermal conductivity (2.141 W/(m·K)) were obtained in the composite PCM. The mass fraction of paraffin in the composite PCM could reach 94% without leakage of liquid paraffin when being heated at 50°C for more than 3 h, and the thermal cycle stability was good. Moreover, the thermal storage and release properties of this composite PCM with different thicknesses were studied by numerical simulation. The results showed that the thermal storage and release time are proportional to the thickness of the composite PCM, and there was almost no temperature gradient during the thermal storage and release process, which indicated that the thermal conductivity of this kind of composite PCM was high enough for building applications. [ABSTRACT FROM AUTHOR]

Abstract Silicon solar cells have been center of focus over the decades while the price challenge still hinders its large-scale application. Cost reduction is the urgent pursuit and our work focuses on the texturization process for mono-crystalline silicon. In this report, nanostructures made by metal-assisted chemical etching (MACE) method were introduced before texturization in low-concentration alkaline solution, which shows the advantage in controlling uniformity and thickness losses compared with standard-concentration alkaline solution. By varying MACE etching time, black silicon layers with different morphologies and depths were obtained. Consequently, pyramid structures of different sizes were observed after texturizaiton. Minimum reflectance value of 10.3% and mean pyramid size of 2.95 µm were achieved in low-concentration alkaline solution with optimized MACE etching time. By using SEM, PL and analytical balance to analyze the morphologies of black silicon samples and corresponding thickness losses, we speculated that the nanostructures of black silicon layers acted as the preferential sites for etching, thus accelerated the texturization process and completed within only 10 min. In summary, low-concentration, short-time and less silicon consumption texturization for mono-crystalline silicon could be achieved using our one-step MACE-induced method, exhibiting great potential in commercial photovoltaics utilization and ultra-thin silicon solar cells. [ABSTRACT FROM AUTHOR]

Abstract In this work, random inverted nanopyramids (INPs) are fabricated as light trapping structures on ultrathin c -Si through a simple and cost-effective wet chemical method, followed by a systematic investigation of the photo-capturing properties of INPs combining experiments and simulations. In comprehensive consideration of thickness loss and light trapping performance, random INPs are applied onto 45 μm ultrathin c -Si solar cell and a high short-current density (Jsc) (36.6 mA/cm2) and energy-conversion efficiency (17.0%) are achieved, which are 0.3 mA/cm2 and 0.13% respectively higher than that in micro pyramid textured one, and our electrical simulation also demonstrates that the advantages of INPs are more obvious on thinner c -Si compared with conventional micro pyramids. Finally, through electrical simulation, INPs textured 45 μm c -Si solar cell is expected to have a large improvement room for efficiency by controlling the front and rear surface recombination velocity. All the findings not only offer additional insight into the light-trapping mechanism in the random INPs but also provide controllable and efficient broadband light harvesters for next-generation cost effective flexible photovoltaics. Graphical abstract Image 1 Highlights • Size control of IPs from nano to microscale was achieved by varying MACE temperature. • Near-Yablonovitch limit absorptance was achieved on 45 μm c-Si by using random IPs. • 45 μm random IPs cell achieve 36.6 mA/cm2 current density and 17.0% efficiency. • A theoretical efficiency of 26.3% can be on 45 μm c-Si by optimization. [ABSTRACT FROM AUTHOR]

Abstract NaY(WO 4) 2 phosphors with different Er3+ doping and Er3+/Li+ co-doping concentrations were prepared via high temperature solid state reaction. X-ray diffraction measurement demonstrated the presence of tetragonal-phase NaY(WO 4) 2 , and no impurity phase was found in Er3+/Li+ co-doped samples. Well-crystallized NaY(WO 4) 2 phosphors showed a fine morphology with particle sizes of 1–6 μm determined by scanning electron microscope. Under excitation at 980 nm, the origins of three emission peaks located at 527 nm (green emission 1), 549 nm (green emission 2) and 665 nm (red emission), respectively, were identified. By introducing Li+, the up-converted (UC) emission intensity was enhanced by 0.5 times and 2 times in green and red emission region, respectively. The enhanced luminescence was attributed to the distortion of the local symmetry around Er3+ due to Li+ incorporation in the lattices. The 2H 11/2 → 4I 15/2 (green emission 1) and 4S 3/2 → 4I 15/2 (green emission 2) transitions of the Er3+ ion presented a temperature dependent behavior from 300 to 30 K and were proposed for temperature sensing (optical thermometry) by using the fluorescence intensity ratio (FIR) method. The FIR data obtained by experiment was well fitted with a theoretical function. A higher maximum value of sensitivity (0.0061 K-1) was obtained in 5% Er3+, 0% Li+ doped sample at 300 K. However, due to the distortion of local crystal field around Er3+ ions caused by the introduction of Li+, the sensitivity value of 5% Er3+ and 1% Li+ co-doped sample was higher than that of Li+ free sample below 270 K, which indicated that appropriate Li+ co-doping could optimize the temperature sensing behaviors of Er3+ doped NaY(WO 4) 2 phosphors. Highlights • Li+ co-doped NaY(WO 4) 2 :Er3+ UC phosphors were successfully synthesized. • 527 nm, 549 nm and 665 nm peaked UC emission bands were observed. • The UC emission intensity was found to be enhanced by introducing Li+ ions. • Li+ co-doping could optimize the temperature sensing behaviors below 270 K. [ABSTRACT FROM AUTHOR]

Abstract Ultrathin c -Si solar cells with light trapping nanostructures attract tremendous research interest for their flexibility and high specific power density. However, the performance of the ultrathin c -Si solar cell is limited by a big light absorption loss due to the reduced thickness. Here, we report a novel ultrathin c -Si solar cell through the direct deposition of TiO 2 electron transporting layer and indium tin oxide (ITO) electrode modified with ultrathin low workfunction (WF) metal subsequently onto random inverted nanopyramids (INPs) texture. The random INPs are fabricated through the well-known two-step Ag assisted chemical etching method followed by a post nanostructure rebuilding process. The TiO 2 thickness, deposition temperature and metal layer thickness are changed to optimize cell performance. With the optimized parameters, a high short-current density (Jsc) (30.66 mA/cm2) and energy-conversion efficiency (11.36%) are achieved on random INPs based 45 μm ultrathin c -Si solar cell by choosing 2 nm Mg layer as the modifying ultrathin metal layer, which are 37.65% and 36.4% respectively higher than that in planar one. All the findings not only offer additional insight into the mechanism of TiO 2 electron transporting layer based ultrathin c -Si solar cell but also introduce a promising new approach for next-generation cost effective flexible photovoltaics. Graphical abstract Image 1 Highlights • TiO 2 electron transporting layer can separate carriers between c -Si and electrode. • Ultrathin metal with low work function is used to modify the work function of ITO. • Efficient light trapping on 45 μm c -Si is realized by inverted nanopyramids (INPs). • 11.36% efficiency is achieved on INPs based 45 μm c -Si cell by using ultrathin Mg. [ABSTRACT FROM AUTHOR]

Abstract It is considered that alkaline elements (such as Na, K, Rb) introduced through post-deposition treatment are able to modify the near-surface region of Cu(InGa)Se 2 thin films. However, research on the effects of Ca element on properties of Cu(InGa)Se 2 thin films is hardly reported. In this paper, Cu(InGa)Se 2 thin films were prepared on quartz glass by e-beam evaporation via two-step process. Study of structural property showed that a certain amount of CaF 2 through post-deposition treatment was beneficial to the uniform composition distribution of Cu(InGa)Se 2 thin films. Near-surface region of Cu(InGa)Se 2 thin films was more Cu-depleted by increasing introduced amount of Ca element. It was inferred that Ca diffused into the Cu(InGa)Se 2 thin films substituted the In sites as Ca In so as to increase the carrier concentration. By calculation, the spike barrier of CdS/Cu(InGa)Se 2 heterojunction was shown to decrease with increased thickness of CaF 2 layers. As a result, Cu(InGa)Se 2 solar cell subjected to 20 nm CaF 2 post-deposition treatment, which possessed higher fill factor, open circuit voltage and short circuit current density, achieved the optimal power conversion efficiency. An efficiency of Cu(InGa)Se 2 solar cell was enhanced by 2.9% after 20 nm CaF 2 post-deposition treatment. Highlights • Well crystallized CIGS thin films were prepared on quartz glass via two-step process. • Ga graded distribution in the films was alleviated after CaF 2 PDT. • Near-surface region of CIGS thin films was more Cu-poor by increasing amount of Ca. • An efficiency of CIGS solar cell was enhanced by 2.9% through 20 nm CaF 2 PDT. [ABSTRACT FROM AUTHOR]

Since challenges still exist in size control fabrication of inverted pyramids (IPs) on c -Si substrate, size difference of IPs among reported literatures still can not be explained reasonably. Here, formation mechanism of IPs from sub-micro scale to micro scale for light trapping on c -Si substrate is reported based on metal assisted chemical etching (MACE) temperature control for the first time. The formation of the IPs is realized through a mask-less Ag assisted wet chemical etching method followed by a post nanostructure rebuilding (NSR) process. It is found that the etching directions on (1 0 0) Si can be influenced by the MACE temperature due to the shrink of Ag nanoparticles at high MACE temperature, leaving behind few pore channels in the deepest region of black silicon layer as nucleation sites. Thus large IPs can be formed during the following NSR process. It is believed that the elucidation of the fundamental formation will speed up the fabrication of wafer-scale c -Si IPs for application in bulk and ultrathin c -Si solar cells. [ABSTRACT FROM AUTHOR]

Amorphous carbon (a-C) films were synthesized on quartz substrates through a hot-filament chemical vapor deposition (HFCVD) method. Effect of filament temperature on the thickness, structural, morphological and electrical properties of a-C films was investigated. Both the crystalline quality and sp 2 content of a-C films increased by raising the filament temperature from 1800 °C to 2000 °C. Sharp increase of the surface roughness was observed as the filament temperature increased from 2000 °C to 2100 °C. The a-C films deposited at the filament temperature of 2000 °C with a high growth rate of 35 nm/min exhibited the optimal quality with a small roughness of 0.546 nm and a low resistivity of 1.67 × 10 −2  Ω·cm. These results indicated that HFCVD is a good method to prepare conductive a-C films rapidly and effectively. [ABSTRACT FROM AUTHOR]