Search

We report an organic luminescent small molecule, Bis(1-phenylisoquinoline) (acetylacetonate) iridium(III) or Ir(piq)2(acac), that can function as a stable and efficient hole selective contact (HSC) for crystalline silicon (c-Si) solar cells. The devices with the Ir(piq)2(acac) HSC exhibit superior charge transport properties and high stability for up to 30 days in the air without packaging. The photovoltaic characteristics with the solution-processed Ir(piq)2(acac) HSC exhibit little dependence on the blade coating speed and film thickness, demonstrating tolerance to coating and thickness variations. Moreover, the series resistance of the solar cells and the surface work function of the Ir(piq)2(acac) HSCs exhibit analogous correlations to the annealing temperature, suggesting that the fill factor (FF) enhancement originates from an upward energy band bending and a reduced barrier height which facilitates hole transport and collection. The conventional c-Si solar cell incorporating an Ir(piq)2(acac) HSC achieves a 17.8% power conversion efficiency (PCE) with a 78.9% FF, both exceeding the reference counterpart with a 16.9% PCE and 76.8% FF. This work opens up possibilities for exploring a variety of organic luminescent small molecules as efficient hole selective contacts in high-efficiency and low-cost silicon photovoltaics. Graphic Abstract

In this study, we report enhancement of terahertz (THz) radiation with indium-tin-oxide (ITO) thin-film deposited on semi-insulating gallium arsenide substrate (SI-GaAs). The amplitude of THz emission from both ITO/SI-GaAs and bare SI-GaAs substrate as a function of optical pump (i) incident angle, (ii) polarization angle, and (iii) power were investigated. The enhancement of peak amplitude of a THz pulse transmitted through the ITO/SI-GaAs sample in comparison to bare SI-GaAs substrate varied from 100% to 0% when the pump incidence angle changed from 0° to 50°. The maximum enhancement ratio of peak amplitude for a coated sample relative to the bare substrate is approximately up to 2.5 times at the minimum pump intensity of 3.6 TW/m2 and gradually decreased to one at the maximum pump intensity of 20 TW/m2. From outcomes of these studies, together with data on surface and material characterization of the samples, we show that THz emission originates from the ITO/GaAs interfaces. Further, both interface-field-induced transient current and field-induced optical rectification contribute to the observed THz signal. Observed enhancement was tentatively attributed to surface-plasmon-induced local field enhancement, coupled with constructive interference of forward and retro-reflected backward THz emission from the ITO/GaAs interfaces. The polarity-flip reported previously for very thin Au-coated GaAs was not observed. This was explained by the wide-bandgap, transparency and lower free carriers of ITO. For best results, the incident angle should be in the range of 0 to 30° and the incident polarization should be 0 to 45°. We further predict that the ITO thin film of suitable thickness or with engineered nanostructures, post-annealed under optimum conditions may lead to further enhancement of THz radiation from ITO-coated semiconductor surfaces.

Chip-scale photonic systems that manipulate free-space emission have recently attracted attention for applications such as free-space optical communications and solid-state LiDAR. Silicon photonics, as a leading platform for chip-scale integration, needs to offer more versatile control of free-space emission. Here we integrate metasurfaces on silicon photonic waveguides to generate free-space emission with controlled phase and amplitude profiles. We demonstrate experimentally structured beams, including a focused Gaussian beam and a Hermite-Gaussian TEM10 beam, as well as holographic image projections. Our approach is monolithic and CMOS-compatible. The simultaneous phase and amplitude control enable more faithful generation of structured beams and speckle-reduced projection of holographic images.

The emerging applications of silicon photonics in free space, such as LiDARs, free-space optical communications, and quantum photonics, urge versatile emission shaping beyond the capabilities of conventional grating couplers. In these applications, silicon photonic chips deliver free-space emission to detect or manipulate external objects. Light needs to emit from a silicon photonic chip to the free space with specific spatial modes, which produce focusing, collimation, orbital angular momentum, or even holographic projection. A platform that offers versatile shaping of free-space emission, while maintaining the CMOS compatibility and monolithic integration of silicon photonics is in pressing need. Here we demonstrate a platform that integrates metasurfaces monolithically on silicon photonic integrated circuits. The metasurfaces consist of amorphous silicon nanopillars evanescently coupled to silicon waveguides. We demonstrate experimentally diffraction-limited beam focusing with a Strehl ratio of 0.82. The focused spot can be switched between two positions by controlling the excitation direction. We also realize a meta-hologram experimentally that projects an image above the silicon photonic chip. This platform can add a highly versatile interface to the existing silicon photonic ecosystems for precise delivery of free-space emission.

In this study, we propose a deep-learning approach to establish the lithographic model for i-line photolithography and develop an optical proximity correction (OPC) algorithm to increase the resolution limit. The applications of RETs are not only on CMOS semiconductor, but also on some metasurface which used to patterning by electron beam lithography. With the OPC algorithm, we are able to manufacture a near-infrared metalens patterning by i-line photolithography in a more efficient and less expensive way.

Dopant-free carrier selective contacts have garnered significant interest for the development of high-efficiency silicon solar cells due to their low-temperature processing and suppression of free-carrier absorption. In this work, we investigate thermally-evaporated molybdenum oxides (MoO x ) functioning as a hole-selective contact (HSC) for silicon heterojunction (Si HJT) solar cells. The high work function of MoO x results in upward energy band bending at the MoO x /n-type Si interface, which facilitates the hole transport and blocks the electron. We compare the optical properties of MoO x with different thickness settings of 3, 10, and 15 nm, where the optical bandgap is fitted via the tauc plot and ranging between 3.46, 3.44, and 3.42 eV, respectively. The absorption spectra of MoO x , MoO x with an intrinsic amorphous silicon (a-Si(i)) layer, and sputtered tin-doped indium oxides (ITO) are also presented. The transmission electron microscopy further reveals a 2.8nm-thick silicon oxides layer in between the MoO x and silicon interface. Preliminary results show that the Si HJT cell with a 15 nm-thick MoO x layer achieves a power conversion efficiency (PCE) of 20.3% and an open-circuit voltage (Voc) of 651.9mV, possibly limited by the pyramidal surface morphology and the a-Si(i) interface passivation layer.

High-efficiency silicon solar cells requires an effective carrier selective contact. Over the past few years, molybdenum trioxide (MoO3) has been widely used as the hole selective contact (HSC) for silicon heterojunction solar cells. The high work function and wide energy gap lead to favorable band bending for hole transport across the MoO3/Si interface. In previous studies, the MoO3 is commonly deposited by thermal evaporation. Here, we propose a simple solution-processed method to form a MoO3 HSC for conventional crystalline silicon (c-Si) solar cells. The crystalline MoO3 nanoparticle solution with a concentration of 2.3-2.7wt% was blade coated on the rear side of an n+/p silicon solar cell without an antireflective coating. By measuring the current-voltage (I-V), contact resistivity (ρ c ), and external quantum efficiency (EQE), we investigate the photoelectric properties of the solar cells incorporating the MoO3 nanoparticle layer. We show that the MoO3 HSC has a low contact resistivity of 29.5 mΩ cm between p-type Si and the silver electrode. The EQE exhibits enahcement on the near-infrared wavelength regime, indicating a field passivation effect. Overall, the n+/p c-Si solar cell incorporating the solution-processed MoO3 HSC exhibits an improved power conversion efficiency (PCE) of 11.8% due to an increased open-circuit voltage (Voc) and fill factor (FF).

The interdigitated back contact (IBC) silicon solar cells such as heterojunction with an intrinsic thin-film (HIT) and polycrystalline silicon on oxide (POLO) have both achieved a record power conversion efficiency (PCE) exceeding 26%. However, the complicated fabrication procedures and high cost currently hinder the deployment of these novel IBC solar cells in the photovoltaic market. Here, we investigate an n-type IBC solar cell architecture incorporating hybrid diffusion and tunnel oxide passivated contacts (TOPCon) to mitigate the fabrication complexity. A Sentaurus TCAD model which takes into account the tunneling mechanism of silicon oxides is developed and validated with a fabricated device. Subsequently, we investigate the impact of design parameters such as the anode/cathode ratio, the anode width with a fixed gap size, and the deviation of the laser contact openings. Based on the correlations between the design parameters and device characteristics, we can choose a practical device design. Finally, we demonstrate an IBC solar cell with a PCE of 20.3% fabricated with an improved metal contact process that lowers the contact resistivity.

High pattern fidelity is paramount to the performance of metalenses and metasurfaces, but is difficult to achieve using economic photolithography technologies due to low resolutions and limited process windows of diverse subwavelength structures. These hurdles can be overcome by photomask sizing or reshaping, also known as optical proximity correction (OPC). However, the lithographic simulators critical to model-based OPC require precise calibration and have not yet been specifically developed for metasurface patterning. Here, we demonstrate an accurate lithographic model based on Hopkin’s image formulation and fully convolutional networks (FCN) to control the critical dimension (CD) patterning of a near-infrared (NIR) metalens through a distributed OPC flow using i-line photolithography. The lithographic model achieves an average ΔCD/CD = 1.69% due to process variations. The model-based OPC successfully produces the 260 nm CD in a metalens layout, which corresponds to a lithographic constant k1 of 0.46 and is primarily limited by the resolution of the photoresist. Consequently, our fabricated NIR metalens with a diameter of 1.5 mm and numerical aperture (NA) of 0.45 achieves a measured focusing efficiency of 64%, which is close to the calculated value of 69% and among the highest reported values using i-line photolithography.

In this work, we observed enhanced terahertz emission from the interface between indium tin oxide (ITO) and semi-insulating gallium arsenide (SI-GaAs) substrate. Further, we investigated the dependence of THz emission on pump power and angle of incident excitation beam. We found more than 3 times of THz emission power enhancement for incident angle below 70°. Besides, we found enhancement of THz radiation at low pump intensity and saturation with increasing peak excitation intensity beyond 20 TW/m2. The experimental results are well explained by plasmonic effects at the metal-semiconductor interface.

High-efficiency solar cells require effective carrier selective contacts which are depicted by their contact resistance and carrier selectivity. Over the past few years, diffusion-free carrier selective contacts have been broadly investigated including a variety of metal oxides, poly (3,4-ethylenedioxythiophene) doped with poly(-styrenesulfonic acid) (PEDOT:PSS), amino acids, alkaline metal salts, etc.. In this work, we investigate a solution-processed, organic small-molecule materials, 2,5,8,11-Tetra-tert-butylperylene (TBPe) to serve as the carrier selective materials. TBPe is fluorescent blue emitters respectively, which have been used as a hole transport layer in organic light emitting diodes. Moreover, the highest occupied molecular (HOMO) level of the material matches to the valance band of Si which may facilitate hole transport in conventional silicon solar cells. The small-molecule material is separately dissolved in chlorobenzene (CB), chloroform (CF) and toluene, followed by blade-coating on to the rear side of a 4 cm2, conventional n+/p silicon solar cell. Without the front anti-reflective coating (ARC) the devices with TBPe achieves a fill factor of 81.6%, and power conversion efficiency (PCE) of 12.6%, respectively. We will present the contact resistance, band alignment, and device efficiency to evaluate the potential of TBPe to serve as the hole selective contact.

Light-weight photovoltaic (PV) modules can be easily integrated into buildings, vehicles, portable electronics, and many other special applications, thus leading to many potential markets for photovoltaics. In this work, we investigate the performance of several conventional and new module materials under damp-heat and pressure cooker tests with 105°C 85% relative humidity (RH) for the development of reliable light-weight PV. The top layer includes the conventional polyethylene terephthalate (PET), ethylene /tetrafluoroethylene (ETFE) sheets and also a biocompatible, weather durable silicone/ polyurethane (PU) composite material, named as Compo-SiL ®, while the bottom layer is the conventional Tedlar/PET/Tedlar (TPT) back sheet. We also compare the performance of a thermal polyurethane (TPU) with the conventional ethylene vinyl acetate (EVA) as the encapsulant. A single 6-inch polycrystalline solar cell is laminated with a combination of the materials above and then undergone the accelerated tests and periodical analyses of electrical performance, change of appearance, electroluminescence imaging. We have found that TPU as an encapsulant performs better than EVA under damp-heat test for 1000 hours, where the power conversion efficiency was not affected at all. However, TPU fails at the pressure cooker test with 105°C and 85% RH. On the other hand, the Compo-SiL ®, a silicone/ polyurethane (PU) composite material as the top layer performs better than the PET and ETFE under the pressure cooker test. The efficiency degradation is less than 10% after 1000 hours. These preliminary results may stimulate further research effort in the development of light-weight PV encapsulation.

Hybrid PEDOT:PSS-silicon heterojunction solar cells have the advantages of low temperature, low cost and solution process. However, as a low-quality native oxide layer can easily form on the surface of silicon substrates, the hybrid solar cells still suffer from charged carrier recombination at the defective interface, hence affecting the device characteristics. In this work, we employ a thermally induced silicon hydrosilylation technique to form a self-assembled monolayer(SAM) on the hydrogen-terminated silicon substrate, in order to prevent the oxidation and passivate the surface of silicon. The quality of this monolayer passivation is characterized by the contact angle, X-ray photoelectron spectroscopy (XPS) analyses. We have found that the SAM passivation can effectively reduce the contact resistance between silicon and the aluminum electrode, leading to an improved open-circuit voltage and fill-factor. However, as the silicon surface with the SAM passivation becomes hydrophobic, it is difficult to apply aqueous PEDOT:PSS solution onto silicon. Therefore, we further apply a low-damage oxygen plasma treatment to modify the terminal functional group of the monolayer to form a hydrophilic surface. The power conversion efficiency of the modified devices is between 10–12%. Although the PCE does not surpass the reference device due to possible chemical reactions between the PEDOT:PSS and SAM, the proposed low- damage oxygen-plasma treatment provide a viable solution for modifying the functional passivation of hybrid PEDOT:PSS silicon solar cells using SAMs.

Recently, hybrid organic silicon heterojunction solar cells have attracted significant interests due to good device performance and simple solution processes. However, electron transport across the cathode interface remains one of the critical issues to be solved. In this study, we employ aluminum-doped zinc oxide (AZO) nanoparticle dispersion to form an electron transport interlayer between the n-type silicon (n-Si) and rear-side aluminum (Al) electrode via blade coating. We further investigate the correlation between the surface morphology and the device characteristics for various furnace annealing conditions: 200°C, 300°C, and 350°C. The hybrid solar cell with the AZO interlayer annealed at 300°C exhibits the highest power conversion efficiency (PCE) of 11.8% with a fill-factor (FF) of 71.3%, where the film morphology shows small and relatively smooth grains revealed by the atomic force microscopy. As a comparison, the reference counterpart without the AZO interlayer exhibits a PCE of 8.5% with a FF of 61.7%. The preliminary results demonstrate the potential of inorganic nanoparticle solution processes for forming a uniform and homogeneous interlayer. Further work on the contact resistance and carrier selectivity of the AZO thin film is still in progress and will be presented.

By using absolute electroluminescence measurement, we characterized current-dependent external radiative efficiency of GaInAs/GaAsP multiple quantum well (MQW) single-junction solar cells with and without a back distributed Bragg reflector (DBR). Internal radiative efficiency ( η int) under illuminated condition was quantified for analyzing their difference in photovoltaic performances. It was revealed that MQWs showed an advantage of improved η int compared with a bulk layer, and that a back DBR indeed improved conversion efficiency via double-pass absorption of sun light, but improvement via reduction of rear radiative emission loss toward substrate was small. Efficiency add-on via improved material quality, or η int, in the same structures was predicted.

Photon management plays a vital role in the power conversion efficiency of III-V semiconductor solar cells. However, the photon recycling characteristics of GaAs-based multi-quantum-well (MQW) solar cells employed different optical designs had yet been fully explored. In this work, we investigate the impact of the spectrally selective filter (SSF) and distributed Bragg reflector (DBR) on the photovoltaic characteristics of single-junction, strain-balanced In0.1Ga0.9As/ GaAs0.85P0.15 MQW solar cells. Specifically, the SSFs with cutoff wavelengths of 880, 910, and 940 nm are designed and implemented on MQW solar cells with and without the incorporation of a rear DBR. Photon confinement in the vertical direction is verified based on the characterizations of reflectance, electroluminescence, and external quantum efficiency. We show that the photon confinement reduces the saturation current density, up to 26 times and 3 times for the 880 nm SSF-MQW and SSF-MQW-DBR devices, respectively, compared to that of the 940 nm devices. Furthermore, by comparing the SSF-MQW-DBR solar cells under simulated one-sun and concentrated illumination conditions, the open-circuit voltage exhibits a maximal net increase for the 910 nm SSF due to tradeoff between the short-circuit and saturation current density. The proposed SSF design may offer a viable approach to boost the performance of GaAs-based MQW solar cells.

Kirigami graphene allows a two-dimensional material to transform into a three-dimensional structure, which constitutes an effective transparent electrode candidate for photovoltaic (PV) cells having a surface texture. The surface texture of an inverted pyramid was fabricated on a Si substrate using photolithography and wet etching, followed by metal-assisted chemical etching to obtain silicon nanowires on the surface of the inverted pyramid. Kirigami graphene with a cross-pattern array was prepared using photolithography and plasma etching on a copper foil. Then, kirigami graphene was transferred onto hybrid heterojunction PV cells with a poly(ethylene terephthalate)/silicone film. These cells consisted of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as the p-type semiconductor, Si(100) as the inorganic n-type semiconductor, and a silver comb electrode on top of PEDOT:PSS. The conductivity of PEDOT:PSS was greatly improved. This improvement was significantly higher than that achieved by the continuous graphene sheet without a pattern. Transmission electron microscopy and Raman spectroscopy results revealed that the greater improvement with kirigami graphene was due to the larger contact area between PEDOT:PSS and graphene. By using two-layer graphene having a kirigami pattern, the power conversion efficiency, under simulated AM1.5G illumination conditions, was significantly augmented by up to 9.8% (from 10.03 to 11.01%).

In this study, we investigate the water vapor transmission rate (WVTR) with highly accelerated stress test (HAST) for the backsheets of the photovoltaic module. According to the Fick’s equation, the WVTR can be fitted by the water concentration of EVA with time dependence. In order to receive the trend of the relative humidity in the photovoltaic module, the flexible printed circuit with high accuracy humidity sensors were embedded in two ethylene-vinyl-acetate (EVA) stacks and laminated with glass and backsheet. Compare to result of the commercial method, this way can reach high accuracy in 3 cycles. However, we get the WVTR of backsheets using dry process in the open air space, but the inhomogeneous temperature and humidity cause the lower WVTR.

In this work, we employ carbon nanotube (CNT) doped PEDOT:PSS to increase the conductivity and evaluate the potential of CNT-doped PEDOT:PSS as a hole selective layer for conventional silicon solar cell. Two types of PEDOT: PSS noted as TC100, TC200 with a relative high and low CNT concentrations. The results have shown that PEDOT: PSS could effectively passivate the silicon surface. The contact resistivity for holes is also smaller than that for electrons on a polished surface. Finally, conventional solar cells with a polished or textured rear surfaces are incorporated with the TC100 and TC200. The results shown that the PEDOT:PSS increase the open-circuit voltage, and short-circuit current, compared to the reference cell. A power conversion efficiency of 14.55% has been achieved for the device with the TC100 hole selective layer.

In this paper, we demonstrate new electrode pattern on rear side of p-type bifacial passivated emitter and rear cells (bifacial-PERC) solar cells for reducing series resistance loss caused by the aluminum grid lines. Cell efficiency of bifacial PERC is enhanced by rear Al grids add multi bus-bar (MBB) or grid segments interconnection. The high J sc and FF value of the PERC+ using local grid with MBB as rear electrodes which increases the J sc by 0.5 mA/cm2 and FF by 2.58 % compare to the PERC+ without rear MBB. The high Jsc and FF value of the PERC+ using local grid with vertical line segments as rear electrodes which increases the J sc by 0.34 mA/cm2 and FF by 3.6 % compare to the PERC+ without vertical line segments. In contrast to the PERC cell, the bifacial PERC cell using localized Al grid on rear side and with thicker back surface field (BSF).

we investigate the potential and stability of perovskite(MaPbI3) as the hole-selective contact materials for silicon solar cells because perovskite has excellent carrier transport properties for both electrons and holes. We have overcome the problem of forming a continuous perovskite thin film on silicon due to low surface energy by engineering the silicon surface roughness and native oxide. As a result, the short-circuit current density (Jsc) of the device with the perovskite layer increases by 0.6mA/cm2 from 27.73 to 28.32 mA/cm2 and the open-circuit voltage (Voc) increases by 5mV from 517.36 to 512.50 mV, reaching a power conversion efficiency of 10.53%. The solar cell with the perovskite(MaPbI3) hole selective layer exhibits better performance than the reference counterpart. Future work will be focused on tuning the composition of the PbBr2 and PbI2 to modify the work function and enlarge the hole selectivity.

The solution p-type doping of various conjugated polymers and small molecules via blending with tetrafluorotetracyano-quinodimethane (F4-TCNQ) is investigated to facilitate hole transport for hybrid organic-silicon-nanowire solar cells. Among all, the highly-fluorescent conjugated polymers such as poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) demonstrate superior transport characteristics, where both the device fill-factor and power conversion efficiency (PCE) are positively correlated with the doping concentration. The best PCE achieves 13.66% from the device with 30% p-doped PFO, compared to the reference at 12.50%. The enhancement is ascribed to the efficient interfacial charge-carrier recombination with minimal energy losses. A vertically graded doping profile is further revealed with F4-TCNQ molecules preferentially accumulated near the silicon surface.

Large-area graphene of high quality and uniformity was successfully grown by chemical vapor deposition (CVD) using surface oxidation treatment of copper foil prior to the graphene growth step. The graphene was transferred to the polyethylene terephthalate (PET) substrate (G/PET) to act as a transparent front electrode of hybrid heterojunction photovoltaic (PV) cells; these cells were based on a structural motif of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) as the p-type semiconductor, GaAs (1 0 0) as the inorganic n-type semiconductor, and a silver comb electrode atop of PEDOT:PSS. By using G/PET as a transparent front electrode, the power conversion efficiency (PCE), under simulated AM1.5G illumination conditions, was greatly enhanced by up to 26% (from 6.85% to 8.60%). All PV characteristics, including open-circuit voltage ( $V_{{\rm oc}}$ ), short-circuit current ( $J_{{\rm sc}}$ ), and fill factor (FF), contributed to this PCE enhancement. The reflectance, external quantum efficiency, and dark current were investigated to explain this observed PCE enhancement. Although two layers of graphene can efficiently reduce the sheet resistance, the reduction of transmittance in multilayer cells resulted in lower short-circuit current density, leading to lower PCE, in comparison with those with only one layer of graphene.

Designing an efficient emitter design is an important step for achieving a highly efficient TPV conversion process. Wavelength-selective emissivity, spectra match between the emitter and TPV cells, and high thermal stability are three main characteristics that must be considered before implementing the emitter. In this work, an indium tin oxide (ITO)/sapphire emitter structure is investigated for TPV application over the temperature range from 200°C to 1000°C. A 1-µm-thick ITO layer is deposited on a 650-µm-thick sapphire substrate. In addition, 50-nm-thick SiO2 is deposited on top of the ITO to enhance the performance of emitter at high temperatures. High-temperature emissivity and absorptivity measurement of the emitter samples are obtained using FTIR and a Hitachi U-4100 spectrophotometer, respectively. The resultant SiO2/ITO/sapphire/stainless-steel planar emitter structure has selective emission with high emissivity of ∼0.8 in the 1–1.6 µm wavelength regime at 1000°C. This emission range lies at the bandgap edge of silicon TPV cells and thus can be used to harness the true potential for making a low-cost thermophotovoltaic system.

We have investigated tunable terahertz (THz) phase shifters that are based on a sandwiched liquid crystal (LC) cell with indium&ndash, tin&ndash, oxide (ITO) nanowhiskers (NWhs) as transparent electrodes. More than 360&deg, of phase shift at 1.0 THz was achieved at a driving voltage as low as ~2.6 V (rms). This is approximately 40 times smaller than that reported in previous works using an electrically tuned LC device. Significance of the NWhs in reducing the required voltage is demonstrated. Overall transmittance of the device is as high as 30%, which is accountable by absorption losses of ITO NWhs, quartz substrate and LC. Experimental results are in good agreement with a theoretical formulism while taking into account super-thick LC cells (~1 mm) and pretilt angles. We also propose and demonstrate a novel THz technique for measuring pretilt angles of liquid crystals.

In this work, we use the metal-assisted chemical etching (MACE) to produce our multi-scale surface textures, namely “Hierarchical structure”, which is combined with micropyramid and nanowires. The templates are modulated through controlling the morphology of silver cluster on the randomly distributed micro-pyramidal surface with rapid thermal annealing (RTA) and the ratio of hydrogen fluoride (HF) and hydrogen peroxide (H 2 O 2 ) during metal-assisted chemical etching. The power conversion efficiency (PCE) of new multi-structure on a hybrid solar cell can achieve 14.07 % by reducing reflectance to 3.61 % and enhancing J SC to 33.43 mA/cm2 with a 1x1 cm2 active area.

InN selective-area-growth on patterned GaN templates was employed by nano-imprint lithography and LPMOCVD epitaxy. ITO rods were deposited by oblique-angle electron beam evaporation. The X-ray diffraction patterns provide the hexagonal orientation of patterned InN crystals. The broad band signal and peak energy blue-shift phenomenon due to higher Fermi-level to acceptor emission were investigated by photoluminescence (PL). The Raman-shifts characterized the high-quality patterned InN growth. InN nanostructures/ITO rods enhanced broadband and angle-independent anti-reflection. It was demonstrated with near-infrared response by a tunable laser illumination (1470 ˜1580 nm), and the portion photocurrent (920 nm long pass) exhibits 33° measured via AM1.5G solar simulated spectra.

In this work, we demonstrate the packaging of hybrid organic - silicon solar cell mini-modules employing flexible and ultrathin transparent conductive films. The unique engineering plastic substrates are printed with high-resolution, micrometer-scaled silver meshes to achieve superior optical transmittance and low sheet resistance, offering the efficient collection of charged carriers through distributed metallic grids. The width of silver grid can be as low as 3 μm, which is a 10 to 15 fold reduction compared to the conventional grid width used in screen printing. By systematically comparing various substrate materials and process conditions, we achieve a power conversion efficiency of 9.5% on 2x2 cm2 mini-modules.

We have carried out multiple analysis on the acceleration factors of LID for Cz-Si PERC cells, including temperatures, intensities and wavelengths at 396nmand 969nm. The recovery time of LID at 130 ° C under 1 SUN shrinks down to 4 hrs and the maximum degradation in Pmax is less than 3 % due the elimination of B-O LID under high carrier-injection. However, it seems that higher intensities couldn’t stop the second degradation from happening, indicating the formation of other defects. Therefore, we employ LED light source of different wavelengths and obtain that both maximum degradation of Pmax are quite different. The consequence implies that behavior of LID might be originated from the particular position (penetration depth) where carriers are located.

The surface textures of hybrid solar cells are composed of inverted microscale pyramidal(IP) and nanowire structures, yielding a low AM1.5G weighted reflectance of 6.4%. The hybrid solar cells incorporating the kirigami graphene clearly show better performance than thosewithout graphene or with planar graphene. The specific pattern made the 2D graphene can highly increase the conformal coverage on silicon texture, seem like the 3D material. Thedevic with two-layer kirigami graphene has exhibits the highest fill factor (FF) of 67.98% and a power conversion efficiency (PCE) of 11.01%, compared to the reference counterpart with an FFof 65.58% and a PC of 10.03%.