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Kesterite-based Cu2ZnSn(S,Se)4(CZTSSe) thin-film solar cells (TFSCs) are a promising candidate for low-cost, clean energy production owing to their environmental friendliness and the earth-abundant nature of their constituents. However, the advancement of kesterite TFSCs has been impeded by abundant defects and poor microstructure, limiting their performance potential. In this study, we present efficient Ag-alloyed CZTSSe TFSCs enabled by a facile metallic precursor engineering approach. The positioning of the Ag nanolayer in the metallic stacked precursor proves crucial in expediting the formation of Cu–Sn metal alloys during the alloying process. Specifically, Ag-included metallic precursors promote the growth of larger grains and a denser microstructure in CZTSSe thin films compared to those without Ag. Moreover, the improved uniformity of Ag, facilitated by the evaporation deposition technique, significantly suppresses the formation of detrimental defects and related defect clusters. This suppression effectively reduces nonradiative recombination, resulting in enhanced performance in kesterite TFSCs. This study not only introduces a metallic precursor engineering strategy for efficient kesterite-based TFSCs but also accelerates the development of microstructure evolution from metallic stacked precursors to metal chalcogenide compounds.

The liquid‐phase‐assisted grain growth (LGG) process is a promising strategy to fabricate large‐grain pure sulfide Cu2ZnSnS4(CZTS) layers that span the absorber thickness and improve the carrier collection efficiency in photovoltaic devices. Li doping is an effective route to promote such LGG process of Cu2ZnSn(S,Se)4(CZTSSe) as it can provide liquid Li‐Se phase facilitating the growth of large‐grain CZTSSe. However, the detailed function of the added Li in grain growth has rarely been investigated in both CZTS and CZTSSe, as the reported in situ, and pre‐depositiondoping strategies usually suffer from substantial Li losses during the spin‐coating process and/or the high‐temperature sulfurization process. Herein, by monitoring the temperature‐dependent Li loss during the sulfurization process, we demonstrate that a small proportion of the added Li can remain at the CZTS film from the early sulfurization stage and provide Li‐S flux to promote the LGG process. An encouraging efficiency of 10.53%, with a remarkably high short‐circuit current density of 22.6 mA/cm2and open‐circuit voltage of 0.744 V, is achieved by a significantly enlarged grain size of 3 μm with Li addition. This work could enhance the knowledge of employing Li‐S as flux for growing large‐grain chalcogenide absorbers for high performance devices with better carrier transport. An enhanced liquid‐phase assisted grain growth (LGG) process for kesterite Cu2ZnSnS4(CZTS) is achieved by adding Li into CZTGS nanoparticle layer at the bottom of sputtered precursor. The LGG process was enhanced by the Li‐S flux from the residual Li at above 350°C, thus significantly improving the carrier collection efficiency and enabling 10.53% efficient Cd‐free CZTS solar cells.

Mixed-halide wide-band gap perovskites (WBPs) still suffer from losses due to imperfections within the absorber and the segregation of halide ions under external stimuli. Herein, we design a multifunctional passivator (MFP) by mixing bromide salt, formamidinium bromide (FABr) with a p-type self-assembled monolayer (SAM) to target the nonradiative recombination pathways. Photoluminescence measurement shows considerable suppression of nonradiative recombination rates after treatment with FABr. However, WBPs still remained susceptible to halide segregation for which the addition of 25% p-type SAM was effective to decelerate segregation. It is observed that FABr can act as a passivating agent of the donor impurities, shifting the Fermi-level (Ef) toward the mid-band gap, while p-type SAM could cause an overweight of Eftoward the valence band. Favorable band bending at the interface could prevent the funneling of carriers toward I-rich clusters. Instead, charge carriers funnel toward an integrated SAM, preventing the accumulation of polaron-induced strain on the lattice. Consequently, n–i–p structured devices with an optimal MFP treatment show an average open-circuit voltage (VOC) increase of about 20 mV and fill factor (FF) increase by 4% compared with the control samples. The unencapsulated devices retained 95% of their initial performance when stored at room temperature under 40% relative humidity for 2800 h.

The effects of WO3intermediate layer on the microstructure, electrical and defects properties of CZTSSe films are revealed for the first time, and high quality CZTSSe crystal and low back interface contact barrier are obtained.

A method for measuring light absorption using photothermal deflection spectroscopy (PDS) is investigated. Typical reflectance and transmittance (R & T) absorption measurements have low spectral resolution (SR) with standard setups. It is believed that absorption measurements using PDS solve this problem because of its high sensitivity, even at a high SR. However, accurate absorption measurements have not been obtained using conventional PDS. The reflectance of the sample must be considered in the absorptance calculations. Various absorption measurement methods are compared and a novel calculation method for accurate PDS absorption measurements is proposed. A sample with quantum structures is fabricated and PDS measurements are performed. Exciton absorption peaks are also observed. The high SR of PDS is demonstrated and the measured exciton absorption peaks are confirmed using piezoelectric photothermal measurements. Furthermore, it is confirmed that the absolute values of absorptance derived from the R & T and PDS measurements agree well. The new PDS absorption measurement technique enables to obtain accurate absorption characteristics, which are indispensable for designing and optimizing optoelectronic devices. This study presents a method for conducting accurate absorption measurements using photothermal deflection spectroscopy (PDS). The surface reflectance must be considered when calculating the absorptance. It is demonstrated how to estimate the reflectance of a sample in a liquid. The light absorptance of a quantum structure with high accuracy is measured by using PDS.

Despite the remarkable advances of inorganic perovskite solar cells (PSCs) by extrinsic metal doping, the doping mechanism and physical location of doping ions are still ambiguous. Herein, the ion-migration behavior of inorganic PSCs is studied theoretically and experimentally for Sm-doped CsPbI2Br perovskites. The structural characterizations and density functional theory (DFT) calculation confirm the interstitial occupancy of the dopant Sm in the CsPbI2Br perovskite lattice. The ion-migration behavior was systematically unveiled by employing multiple photoelectrochemical techniques. The results show that with Sm interstitial doping in the CsPbI2Br perovskite, the operational stability of PSCs is dramatically improved owing to effectively suppressed ion migration, demonstrated by alleviated VOCchange at different scan rates, weaker response to electric poling, faster photocurrent response, higher activation energy of mobile ions, and much more stable maximum power point (MPP) tracking performance. With theoretical model-supported experimental investigation, this research unravels the mechanism of ion-migration suppression in CsPbI2Br PSCs by interstitial doping. This may pave the way to achieve operational stability of PSCs through facile cost-effective practice.

Spiro-OMeTAD, one of the most widely used hole-transport materials (HTMs) in optoelectronic devices, typically requires chemical doping with a lithium compound (LiTFSI) to attain sufficient conductivity and efficient hole extraction. However, the doping step requires an activation process that comprises exposure of the blend films to an ambient atmosphere. Additionally, the lithium dopant induces crystallization, and its hygroscopic nature negatively impacts device performance and lifetime. Here we report a facile approach based on the incorporation of a low-cost alkylthiol additive (1-dodecanethiol, DDT) in the spiro-OMeTAD HTM. We discover that DDT provides a more efficient and controllable doping process with significantly reduced doping duration, enabling the HTM to achieve comparable performance before air activation. The coordination between DDT and LiTFSI increases the concentration of dopants in the HTM bulk, reduces their accumulation at interfaces, and enhances the structural integrity of the HTM under wetting, heat and light stress. We fabricate perovskite solar cells using DDT-treated spiro-OMeTAD as the HTM. Our best devices exhibit a certified power conversion efficiency of 23.1%. Furthermore, the devices can retain 90% of peak performance under continuous illumination for 1,000 h. Our findings represent an important step forward in the production of doped spiro-OMeTAD, as well as its reliable application and future device commercialization.

The Schottky back-contact barrier at the Mo/Cu(In,Ga)Se2(CIGS) interface is one of the critical issues that restrict the photovoltaic performance of CIGS solar cells. The formation of a MoSe2intermediate layer can effectively reduce this back-contact barrier leading to efficient hole transport. However, the selenium-free atmosphere is unfavorable for the formation of the desired MoSe2intermediate layer if the CIGS films are prepared by the commonly used direct sputtering process. In this work, high-efficiency CIGS solar cells with a MoSe2intermediate layer were fabricated by the direct sputtering process without a selenium atmosphere. This is enabled by an intermediate CIGS layer deposited on the Mo substrate at room temperature before being ramped to a high temperature (600 °C). The room-temperature-deposited amorphous CIGS intermediate layer is Se rich, which reacts with the Mo substrate and forms very thin MoSe2at the interface during the high-temperature process. The formed MoSe2decreased the CIGS/Mo barrier height for better hole transport. Consequently, the CIGS solar cell with an 80 nm intermediate layer achieved a power conversion efficiency of up to 15.8%, which is a benchmark efficiency for the direct sputtering process without Se supply. This work provides the industry a new approach for commercialization of directly sputtered CIGS solar cells.

In kesterite solar cells, unfavourable band alignment and interface defects lead to a recombination loss at the heterojunction, thereby limiting light-to-electricity conversion efficiency. The recent strategies for optimizing the heterojunction in kesterite are summarized in this review.

This report addresses indium oxide doped with titanium and tantulum with high near-infrared transparency to potentially replace the conventional indium tin oxide transparent electrode used in semitransparent perovskite devices and top cells of tandem devices. The high near-infrared transparency of this electrode is possibly explained by the lower carrier concentration, suggesting less defect sites that may sacrifice its optical transparency. Incorporating this transparent electrode into semitransparent perovskite solar cells for both the top and bottom electrodes improved the device performance through possible reduction of interfacial defect sites and modification in energy alignment. With this indium oxide-based semitransparent perovskite top cell, we also demonstrated four-terminal perovskite–silicon tandem configurations with improved photocurrent response in the bottom silicon cell.

We demonstrate a monolithic tandem solar cell by sequentially depositing a higher-bandgap (2.3 eV) CH3NH3PbBr3subcell and a lower-bandgap (1.55 eV) CH3NH3PbI3subcell bandgap perovskite cells, in conjugation with a solution-processed organic charge carrier recombination layer, which serves to protect the underlying subcell and allows for voltage addition of the two subcells. Owing to the low-loss series connection, we achieve a large open-circuit voltage of 1.96 V. Through optical and electronic modeling, we estimate the feasible efficiency of this device architecture to be 25.9%, achievable with integrating a best-in-class CH3NH3PbI3sub cell and a 2.05 eV wide bandgap perovskite cell with an optimized optical structure. Compared to previous reported all-perovskite tandem cells, we solely employ Pb-based perovskites, which although have wider band gap than Sn based perovskites, are not at risk of instability due to the unstable charge state of the Sn2+ion. Additionally, the bandgap combination we use in this study could be an advantage for triple junction cells on top of silicon. Our findings indicate that wide band gap all-perovskite tandems could be a feasible device structure for higher efficiency perovskite thin-film solar cells.

The objective of this study is to investigate the beneficial effects and underlying mechanism of dietary β-mannanase supplementation on the productive performance of laying hens fed with metabolic energy (ME)-reduced diets. A total of 448 Hy-Line gray laying hens were randomly assigned to seven groups. Each group had 8 replicates with 8 hens. The groups included a control diet (CON) with a ME of 2750 kcal/Kg, diets reduced by 100 kcal/Kg or 200 kcal/Kg ME (ME_100or ME_200), and diets with 0.15 g/Kg or 0.2 g/Kg β-mannanase (ME_100+β-M_0.15, ME_100+β-M_0.2, ME_200+β-M_0.15, and ME_200+β-M_0.2). The productive performance, egg quality, intestinal morphology, inflammatory response, mRNA expression related to the Nuclear factor kappa B (NF-κB) and AMPK pathway, and cecum microbiome were evaluated in this study. ME-reduced diets negatively impacted the productive performance of laying hens. However, supplementation with β-mannanase improved FCR, decreased ADFI, and restored average egg weight to the level of the CON group. ME-reduced diets increased the levels of interleukin-1β (IL-1β) and IL-6 while decreasing the levels of IL-4 and IL-10 in the jejunum of laying hens. However, dietary β-mannanase supplementation improved jejunum morphology, reduced pro-inflammatory cytokine concentrations, and increased levels of anti-inflammatory factors in laying hens fed with ME-reduced diets. The mRNA levels of IL-6, IFN-γ, TLR4, MyD88, and NF-κBin the jejunum of ME-reduced diets were significantly higher than that in CON, dietary β-mannanase supplementation decreased these genes expression in laying hens fed with ME-reduced diets. Moreover, dietary β-mannanase supplementation also decreased the mRNA levels of AMPKαand AMPKγ, and increased the abundance of mTORin the jejunum of laying hens fed with ME-reduced diets. Cecum microbiota analysis revealed that dietary β-mannanase increased the abundance of various beneficial bacteria (e.g., g_Pseudoflavonifractor, g_Butyricicoccus, and f_Lactobacillaceae) in laying hens fed with ME-reduced diets. In conclusion, dietary β-mannanase supplementation could improve the productive performance of laying hens fed with a ME-reduced diet by improving intestinal morphology, alleviating intestinal inflammation, changing energy metabolism-related signaling pathways, and increasing cecum-beneficial microbiota.

A cation substitution in Cu2ZnSn(S,Se)4(CZTSSe) offers a viable strategy to reduce the open-circuit voltage (Voc)-deficit by altering the characteristics of band-tail states, antisite defects, and related defect clusters. Herein, we report a facile single process, i.e., simply introducing a thin Ag layer on a metallic precursor, to effectively improve the device characteristics and performances in kesterite (Agx,Cu1–x)2ZnSn(Sy,Se1–y)4(ACZTSSe) solar cells. Probing into the relationship between the external quantum efficiency derivative (dEQE/dλ) and device performances revealed the Voc-deficit characteristics in the ACZTSSe solar cells as a function of Cu and Ag contents. The fabricated champion ACZTSSe solar cell device showed an efficiency of 12.07% and a record low Voc-deficit of 561 mV. Thorough investigations into the mechanism underpinning the improved performance in the ACZTSSe device further revealed the improved band-tailing characteristic, effective minority carrier lifetime, and diode factors as well as reduced antisite defects and related defect clusters as compared to the CZTSSe device. This study demonstrates the feasibility of effectively suppressing antisite defects, related defect clusters, and band-tailing characteristics by simply introducing a thin Ag layer on a metallic precursor in the kesterite solar cells, which in turn effectively reduces the Voc-deficit.

The one-dimensional photovoltaic absorber material Sb2S3requires crystal orientation engineering to enable efficient carrier transport. In this work, we adopted the vapor transport deposition (VTD) method to fabricate vertically aligned Sb2S3on a CdS buffer layer. Our work shows that such a preferential vertical orientation arises from the sulfur deficit of the CdS surface, which creates a beneficial bonding environment between exposed Cd2+dangling bonds and S atoms in the Sb2S3molecules. The CdS/VTD-Sb2S3interface recombination is suppressed by such properly aligned ribbons at the interface. Compared to typical [120]-oriented Sb2S3films deposited on CdS by the rapid thermal evaporation (RTE) method, the VTD-Sb2S3thin film is highly [211]- and [121]-oriented and the performance of the solar cell is increased considerably. Without using any hole transportation layer, a conversion efficiency of 4.73% is achieved with device structure of indium tin oxide (ITO)/CdS/Sb2S3/Au. This work provides a potential way to obtain vertically aligned thin films on different buffer layers.

The low energy density of supercapacitors (SCs) is one of the main factors restricting their development. WO3with high theoretical capacitance is an ideal n-type material for anode electrode, but its narrow potential window and low conductivity are not conducive to the application of high-energy-density SCs. Herein, a high electrochemical activity poly(indole-5-carboxylic acid) (P5-ICA) as p-type material wrapping n-type oxygen vacancies WO3vertically nanowire arrays supported on carbon cloth is prepared by hydrothermal method and subsequent electrodeposition method. This adhesive free flexible p/n-type hetero-structural P5-ICA@WO3vertical nanowire array electrode has a three-dimensional porous nanostructure that not only provides a large surface area, but also promotes the penetration of electrolyte ions and the transmission of electrons. It is found that the P5-ICA@WO3nanowire array with high areal specific capacitance (1430 mF cm−2at 4 mA cm−2) and long cycle stability (94 % after 6000 cycles) exhibits a widened electrochemical activity window compared to individual material. The symmetrical SCs assembled using P5-ICA@WO3can provide a high areal energy density of 137.6 μWh cm−2at the power density of 1.4 mW cm−2, which is significantly higher than the SCs performance of previously used WO3-based electrode materials.

Kesterite Cu2ZnSnS4(CZTS) photovoltaics have been comprehensively investigated in the past decades but are still hampered by a relatively large open circuit voltage (Voc) deficit, which is correlated to bulk defects in CZTS and interface recombination. Heterojunction interface management is of critical importance to tackle the interface recombination. In this work, we use atomic layer deposition (ALD) to synthesize a wide range of Zn1–xSnxO (ZTO, 0 ≤ x≤ 1) films for application as a buffer layer in CZTS solar cells. A favorable band alignment is achieved using a 10 nm Zn0.77Sn0.23O buffer layer that enabled an impressive 10% increase in open circuit voltage of the CZTS solar cell. The microstructure and chemical nature of the CZTS/ZTO interface are carefully studied and the presence of an ultrathin Zn(S, O) tunnel layer is demonstrated. The decreased interfacial defects stemming from the minor lattice mismatch at the CZTS/Zn(S,O)/ZTO heterointerface in combination with the passivation provided by a higher sodium concentration throughout the CZTS/ZTO device explains the significant increase in open circuit voltage. Finally, we demonstrate a CZTS solar cell efficiency of 9.3%, which is the highest efficiency for Cd-free pure sulfide CZTS solar cell to date to the best of our knowledge.

Multijunction solar cells (MJSCs) are capable of converting sunlight to electricity more efficiently than single-junction solar cells. The intermediate scattering layers between the individual junctions contribute to high efficiency by impacting the generated currents, photon recycling (PR), as well as luminescent coupling (LC) in the device. The MJSC efficiency can be simulated using expressions that involve a simplified and idealized intermediate layer structure but cannot accurately reflect its actual performance. This work, however, aims to establish a systematic optical model for MJSCs with complicated intermediate layers. It begins with incorporating the LC and PR effects into the developed model, emphasizing requirements for the cut-off wavelength and long-wavelength transmission of the intermediate layer. Furthermore, a three-dimensional metallic nanocylinder array is designed as the intermediate layer to improve device performance. With the model, high-performance MJSCs can be designed and optimised by quantifying the impact of PR and LC on device parameters.

Molybdenum (Mo) thin films are still a dominant choice for the back contact layer of Cu(In,Ga)Se2(CIGS) and Cu2ZnSnS4(CZTS) solar cells. This paper presents a review of Mo back contacts for CIGS and CZTS solar cells, including the requirements for a good back contact, the reason for the choice of Mo, and post-treatment. Additionally, a Mo bilayer back contact was fabricated by varying the argon (Ar) pressure during sputtering to provide both low resistivity and good adhesion to the soda-lime glass substrate. The effects of vacuum thermal annealing on the electrical, morphological and structural properties of the Mo bilayer were also investigated. Vacuum thermal annealing was seen to densify the Mo bilayer, reduce the sheet resistance, and improve the bilayer’s adhesion to the soda-lime glass. The Mo bilayer back contact with a low sheet resistance of 0.132 Ω/□ and strong adhesion was made for chalcogenide- and kesterite-based solar cells.

A low-temperature solution-based process for depositing silver nanowire (AgNW) networks for use as transparent conductive top electrode is demonstrated. These AgNWs when applied to Cu2ZnSnS4solar cells outperformed indium tin oxide as the top electrode. Thinner nanowires allow the use of lower temperatures during processing, while longer wires allow lowered sheet resistance for the same surface coverage of NWs, enhancing the transmittance/conductance trade-off. Conductive atomic force microscopy and percolation theory were used to study the quality of the NW network at the microscale. Our optimized network yielded a sheet resistance of 18 Ω/□ and ∼95% transmission across the entire wavelength range of interest for a deposition temperature as low as of 60 °C. Our results show that AgNWs can be used for low-temperature cell fabrication using cheap solution-based processes that could also be promising for other solar cells constrained to low processing temperatures such as organic and perovskite solar cells.

We present the hybrid silver nanowire network–ultrathin ITO as the transparent conductive electrode for earth-abundant and environmentally friendly pure sulfide Cu2ZnSnS4solar cells, replacing the scarce and expensive ITO. For this new hybrid transparent electrode, sputtered intrinsic zinc oxide is introduced as an antireflective coating replacing MgF2in traditional Cu2ZnSnS4solar cells. Random arrays of silver nanowire network with different densities hybridized with 20 nm ITO layer are employed in Cu2ZnSnS4devices and their device performance is compared with the reference device with conventional ITO electrode. The devices with the hybrid electrodes with similar sheet resistance to ITO show generally improved current density due to their better optical transparency than ITO while maintaining similar fill factor. Cu2ZnSnS4devices with low density Ag  nanowire hybrid electrode give the highest efficiency of 6.4% on average mainly due to improved current density, among which the highest efficiency value is 6.72%. Here, 20 nm intrinsic zinc oxide is selected as an antireflective coating based on optical FDTD simulations, which gives an additional 5% increase in current density and efficiency. A Cu2ZnSnS4device with the low density hybrid electrode is improved from 6.72 to 6.84% after introducing an intrinsic zinc oxide antireflective coating layer.

Metal halide perovskite solar cells (PSCs) have undergone rapid progress. However, unstable performance caused by sensitivity to environmental moisture and high temperature is a major impediment to commercialization of PSCs. In the present work, a low-temperature, glass–glass encapsulation technique using high performance polyisobutylene (PIB) as the moisture barrier is investigated on planar glass/FTO/TiO2/FAPbI3/PTAA/gold perovskite solar cells. PIB was applied as either an edge seal or blanket layer. Electrical connections to the encapsulated PSCs were provided by either the FTO or Au layers. Results of a “calcium test” demonstrated that a PIB edge-seal effectively prevents moisture ingress. A shelf life test was performed and the PIB-sealed PSC was stable for at least 200 days. Damp heat and thermal cycling tests, in compliance with IEC61215:2016, were used to evaluate different encapsulation methods. Current–voltage measurements were performed regularly under simulated AM1.5G sunlight to monitor changes in PCE. The best results we have achieved to date maintained the initial efficiency after 540 h of damp heat testing and 200 thermal cycles. To the best of the authors’ knowledge, these are among the best damp heat and thermal cycle test results for perovskite solar cells published to date. Given the modest performance of the cells (8% averaged from forward and reverse scans) especially with the more challenging FAPbI3perovskite material tested in this work, it is envisaged that better stability results can be further achieved when higher performance perovskite solar cells are encapsulated using the PIB packaging techniques developed in this work. We propose that heat rather than moisture was the main cause of our PSC degradation. Furthermore, we propose that preventing the escape of volatile decomposition products from the perovskite solar cell materials is the key for stability. PIB encapsulation is a very promising packaging solution for perovskite solar cells, given its demonstrated effectiveness, ease of application, low application temperature, and low cost.

An electron transport layer is essential for effective operation of planar perovskite solar cells. In this Article, PW12–TiO2composite was used as the electron transport layer for the planar perovskite solar cell in the device structure of fluorine-doped tin oxide (FTO)-glass/PW12–TiO2/perovskite/spiro-OMeTAD/Au. A proper downward shift of the conduction band minimum (CBM) enhanced electron extraction from the perovskite layer to the PW12–TiO2composite layer. Consequently, the common hysteresis effect in TiO2-based planar perovskite solar cells was significantly reduced and the open circuit voltage was greatly increased to about 1.1 V. Perovskite solar cells using the PW12–TiO2compact layer showed an efficiency of 15.45%. This work can contribute to the studies on the electron transport layer and interface engineering for the further development of perovskite solar cells.

Back contact modification plays an important role in improving energy conversion efficiency of Cu2ZnSnS4(CZTS) thin film solar cells. In this paper, an ultrathin carbon layer is introduced on molybdenum (Mo)-coated soda lime glass (SLG) prior to the deposition of CZTS precursor to improve the back contact and therefore enhance CZTS solar cell efficiency. By introducing this layer, the short circuit current (Jsc) and device conversion efficiency increase for both nonvacuum (sol–gel) and vacuum (sputtering) methods. Specifically, for the sol–gel based process, Jscincreases from 13.60 to 16.96 mA/cm2and efficiency from 4.47% to 5.52%, while for the sputtering based process, Jscincreases from 17.50 to 20.50 mA/cm2and efficiency from 4.10% to 5.20%. Furthermore, introduction of this layer does not lead to any deterioration of either open circuit voltage (Voc) or fill factor (FF).

Various characterization methods are implemented to investigate the fundamental properties of a Cu2ZnSnS4(CZTS) solar cell. The chemical distribution across the CZTS grain boundaries, the surface potential of CZTS absorber, the minority lifetime, the carrier collection length, diode ideality factor, dark saturation current, and series resistance are revealed in the characterization measurement. The short minority lifetime, high defect density, and large series resistance are confirmed and need to be addressed in the future work for further efficiency improvement.

A facile sol–gel and selenization process has been demonstrated to fabricate high-quality single-phase earth abundant kesterite Cu2ZnSn(S,Se)4(CZTSSe) photovoltaic absorbers. The structure and band gap of the fabricated CZTSSe can be readily tuned by varying the [S]/([S] + [Se]) ratios via selenization condition control. The effects of [S]/([S] + [Se]) ratio on device performance have been presented. The best device shows 8.25% total area efficiency without antireflection coating. Low fill factor is the main limitation for the current device efficiency compared to record efficiency device due to high series resistance and interface recombination. By improving film uniformity, eliminating voids, and reducing the Mo(S,Se)2interfacial layer, a further boost of the device efficiency is expected, enabling the proposed process for fabricating one of the most promising candidates for kesterite solar cells.

The past two years have seen the uniquely rapid emergence of a new class of solar cell based on organic–inorganic halide perovskite. Although less explored than its tri-iodide counterparts, CH3NH3PbBr3has a larger bandgap of 2.3 eV with a higher voltage potential that is suitable for tandem solar cell applications. In this paper, we report a vapor-assisted method for depositing and fully crystallizing CH3NH3PbBr3film on mesoporous TiO2with good coverage. CH3NH3PbBr3fabricated using this method has demonstrated long carrier diffusion length (>1 μm) as estimated by transient photoluminescence-quenching measurements. We demonstrate solar cells fabricated using such films and spiro-OMeTAD as the hole transport layer with an averaged (from forward and reverse scans) conversion efficiency of 8.7%, Vocof 1.45 V, Jscof 9.75 mA/cm2, and fill factor of 61.5%.

We report on efforts to design high-efficiency silicon homojunction subcells for use in multijunction stack devices. Both simulation and experimental works have been performed looking at a silicon solar cell under a truncated spectrum below 1.5 eV filtered by the upper layers in the multijunction stack. Good agreement is seen between the modeling and experimental results, identifying different emitter design requirements when the solar cell operates under a full or truncated spectrum. A well-passivated front surface, i.e., with low-interface surface recombination velocity, required a lightly doped emitter profile to maximize open-circuit voltage (Voc), while a high-interface recombination surface requires a heavily doped for higher Voc values. The impact on short-circuit current density (Jsc) is found to be minimal, even with large variations in the interface recombination and emitter profiles. In a tandem stack, an interface with low- and high-interface recombination velocities would require lightly doped and intermediate-doped emitters, respectively, for maximum conversion efficiency (η).

Copper (Cu) is present not only in the electrode for inverted-structure halide perovskite solar cells (PSCs) but also in transport layers such as copper iodide (CuI), copper thiocyanate (CuSCN), and copper phthalocyanine (CuPc) alternatives to spiro-OMeTAD due to their improved thermal stability. While Cu or Cu-incorporated materials have been effectively utilized in halide perovskites, there is a lack of thorough investigation on the direct reaction between Cu and a perovskite under thermal stress. In this study, we investigated the thermal reaction between Cu and a perovskite as well as the degradation mechanism by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Kelvin probe force microscopy (KPFM). The results show that high temperatures of 100 °C induce Cu to be incorporated into the perovskite lattice by forming “Cu-rich yet organic A-site-poor” perovskites, (CuxA1–x)PbX3, near the grain boundaries, which result in device performance degradation.

The prediction of the important running variables of blast furnaces (BF) has been a major study subject as one of the most important means for monitoring the BF state in ferrous metallurgical industry. In this paper, a prediction model for BF by integrating a neural network (NN) with partial least square (PLS) regression is presented. The selection of influencing operational parameters of BF on variables to be predicted is developed according to the minimization of residuals based on the theory of path analysis. The selected influencing parameter data series are processed as the inputs of the prediction model. In order to validate this prediction model, the silicon content in hot metal of BF is taken as the variable to be predicted. The model is trained and evaluated with industrial data, and the results show that it works well. Further modification of this prediction model is also discussed to improve its industrial application.

Boron is an excellent dopant for forming germanium (Ge) shallow junctions because of its low diffusivity. This work investigates fabricating heavily boron-doped hydrogenated polycrystalline Ge thin films with an aim to develop a thin emitter of the bottom cell of a monolithic tandem solar cell. The films were deposited on glass by cosputtering in an argon and hydrogen mixture at . Rapid thermal annealing at for 60 s enhances the boron activation level from to . The high activation level obtained with a low thermal budget indicates that the simple fabrication approach is promising.

Theoretical calculation suggests Cu-rich chalcopyrite absorbers contain less defects and have potential to achieve better performance than Cu-poor absorbers. However, this has not been demonstrated due to the detrimental Cu2-xSe impurity remaining in the absorber. Here, we report highly efficient Cu-rich chalcopyrite solar cells by selenizing dimethylformamide molecular precursor solution processed precursor films under high Ar pressure. Characterizations using XRD, Raman, SEM, TEM, c-AFM, PL, and glow discharge optical emission spectroscopy (GDOES) show high pressure selenization enables high quality Cu-rich chalcopyrite absorber materials with stoichiometric composition, smooth surface, high conductivity, and Cu2-xSe free grain boundaries, leading to efficient CuIn(S,Se)2and Cu(In,Ga)(S,Se)2devices with power conversion efficiency of 14.5% and 15.2%, both are the best performing chalcopyrite solar cells from non-hydrazine solutions. Our results demonstrate high Ar pressure selenization is a new strategy to fabricate high quality Cu-rich absorber which has great potential to further improve chalcopyrite solar cell efficiency.

Development of non‐coke ironmaking process in China is presented. It is concluded that coal‐based rotary kiln is still the main process for direct reduced iron (DRI) production in the near future in China. The most important problems of DRI production in China are small production scale and heavy environment pollution. Now the gas‐based shaft furnace process has become one of the significant processes of DRI production in China. The market demand for DRI production in China is continuously increasing. Due to the tense supply of coking coal and its heavy environmental load, more steel plants in China will use smelting reduction (SR) technology.

Highly efficient, ultrathin (~400 nm) pure sulfide kesterite Cu2ZnSnS4(CZTS) solar cells have been realized by interface reaction route controlling and self-organized nano-pattern at the back contact. The Al2O3intermediate layer introduced at the Mo/CZTS interface can effectively inhibit the detrimental interfacial reaction between CZTS and Mo in the initial stage of sulfurization, and then turns into a self-organized nanopattern yielding a nanoscale opening for electrical contact. With this interface modification, the traditional issues of phase segregation (secondary phases) and voids at the back contact region can be well addressed, which greatly improves uniformity and reduces back contact recombination. As a result, this interface modification not only leads to beyond 8% ultrathin CZTS solar cells but also yields two certificated world record efficiencies: 9.26% for 0.237 cm2small area and 7.61% for 1 cm2standard kesterite CZTS solar cells (normal thickness).

Boron is an excellent dopant for forming germanium (Ge) shallow junctions because of its low diffusivity. This work investigates fabricating heavily boron-doped hydrogenated polycrystalline Ge thin films with an aim to develop a thin p+emitter of the bottom cell of a monolithic tandem solar cell. The films were deposited on glass by cosputtering in an argon and hydrogen mixture at 500°C. Rapid thermal annealing at 600°Cfor 60 s enhances the boron activation level from 6.24×1019to 1.21×1020atoms/cm3. The high activation level obtained with a low thermal budget indicates that the simple fabrication approach is promising.