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Development of ultra-thin doped poly-Si via LPCVD and ex-situ tube diffusion for passivated contact solar cell applications
摘要： Rear side application of polycrystalline silicon (poly-Si) passivated contacts has demonstrated very high efficiencies for single-junction monocrystalline silicon (mono-Si) solar cells. To further improve the device performance, one possible approach is to apply the passivated contact concept to the front side of the solar cell as well. The front side application requires the use of ultra-thin poly-Si layer in order to suppress parasitic absorption. Suitable ex-situ diffusion process should be developed accordingly without damaging the passivation provided by the very thin interface oxide (iOx). In this work, we prepared symmetric lifetime samples of ultra-thin poly-Si (<30 nm) via low pressure chemical vapour deposition (LPCVD) method. Then we studied and optimised the ex-situ POCl3/BBr3 diffusion doping processes. An excellent passivation quality was demonstrated with a high implied open-circuit voltage (iVoc) of up to 730 mV (on symmetric n+ poly-Si lifetime samples) and 700 mV (on symmetric p+ poly-Si lifetime samples). For possible contact formation, we capped the poly-Si with sputter-deposited ZnO:Al, which shows good opto-electrical properties and firing stability at 650 °C.
关键词： Diffusion,ZnO:Al,Ex-situ doping,Ultra-thin poly-Si,Passivated contact
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Wet-Chemically Textured Ultra-Thin GaAs Solar Cells with Dielectric/Metal Rear Mirrors
摘要： The rear-side contact layer of ultra-thin GaAs solar cells was textured using a simple, one-step wet chemical approach. A ZnS/Ag double layer was conformally deposited to function as a diffusive rear mirror. Local Ohmic contact points provided electrical contact directly to the Ag. The textured solar cells were compared with planar reference cells fabricated on the same wafer and a clear enhancement of long-wavelength quantum efficiency and short-circuit current was observed in the textured cells. Both architectures showed FF > 80% and VOC > 1 V. Additionally, the rear-side texture increases the external luminescent efficiency by enhancing outcoupling of luminescence.
关键词： light trapping,ultra-thin GaAs solar cells,dielectric mirror,wet etching
更新于2025-09-23 15:19:57
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Switchable Photocurrent Generation in an Ultra-thin Resonant Cavity Solar Cell
摘要： Fabry-Perot type resonant nanocavities allow for broadband enhancement of light absorption in ultra-thin absorber layers. By introducing a switchable mirror, these thin film structures can be used as unique optical devices enabling interesting applications with switchable absorption. We use a thin film photovoltaic layer stack based on an amorphous germanium absorber layer and combine it with a thin Mg/Pd mirror to create a switchable solar cell. In this work we demonstrate, how we can switch the light absorption and hence the photocurrent generation of the thin film solar cell by changing the refractive index of Mg, due to hydrogen absorption. Our results show, how optical resonances in the absorber can be switched “on / off” by the change of optical properties of the magnesium reflector. The multi-layer system can be switched from a light absorbing and photocurrent generating state to a transparent window state with excellent color neutrality. We emphasize our study as an important step towards the realization of switchable photovoltaic windows, which paves the way for larger scale building integrated photovoltaic applications.
关键词： Ultra-thin absorber,light trapping,photovoltaic,amorphous germanium,switchable magnesium mirror,smart window
更新于2025-09-23 15:19:57
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Monolayer single crystal two-dimensional quantum dots via ultrathin cutting and exfoliating; è??è?????????????￥?|?????¤?????±????????o???′é???-???1;
摘要： Two-dimensional (2D) atomically thin quantum dots (QDs) possess extraordinary electrical and optical properties. However, fabricating high quality 2D QDs via a universal and reliable technique remains a challenge. Here, we report a simple strategy to prepare high quality, monolayer single crystal 2D QDs via ultrathin cutting 2D bulk single crystals by ultramicrotome, followed by an exfoliation process. The as-prepared 2D QDs have pristine surface, high quality, high monolayer yield and high photoluminescence quantum yield (the highest photoluminescence quantum yield of WS2 is 18%), which can be used as promising, low toxic, biocompatible, and good cell-permeability fluorescent labeling agents for in vitro imaging.
关键词： photoluminescence quantum yield,ultra-thin cutting,single crystal,two-dimension,quantum dots
更新于2025-09-23 15:19:57
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Synthesis of surface-replicated ultra-thin silica hollow nanofibers using structurally different carbon nanofibers as templates
摘要： Ultra-thin silica hollow nano?bers were successfully synthesized using three kinds of well-de?ned carbon nano?bers (CNFs) with di?erent surface structures as e?ective templates via pyrolysis of polycarbomethylsilane-coated CNFs. The prepared silica hollow nano?bers replicated the characteristic surface morphologies of the CNFs, such as herringbone, platelet, and tubular types with edge or basal planes. Especially, the unique HCNF template, with tiny ?bril aggregates on the surface, was the most e?ective template material for synthesizing ultra-thin silica hollow nano?bers with uniform and hierarchical meso-pores and high surface areas (over than 680 m2/g). The chemical and physical properties of the silica nano?bers were evaluated with various analytical techniques, such as TGA, HR-TEM, FE-SEM, XRD, XPS, and N2 adsorption/desorption, and discussed in detail.
关键词： Carbon nano?ber,Template synthesis,Mesoporous ultra-thin silica hollow nano?ber
更新于2025-09-19 17:15:36
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Effect of bending test on the performance of CdTe solar cells on flexible ultra-thin glass produced by MOCVD
摘要： The development of lightweight and flexible solar modules is highly desirable for high specific power applications, building integrated photovoltaics, unmanned aerial vehicles and space. Flexible metallic and polyimide foils are frequently used, but in this work an alternative substrate with attractive properties, ultra-thin glass (UTG) has been employed. CdTe solar cells with average efficiency reaching 14.7% AM1.5G efficiency have been produced on UTG of 100 μm thickness. Little has been reported on the effects on PV performance when flexed, so we investigated the effects on J-V parameters when the measurements were performed in 40 mm and 32 mm bend radius, and in a planar state before and after the bend curvature was applied. The flat J-V measurements after 32 mm bending test showed some improvement in efficiency, Voc and FF, with values higher than the first measurement in a planar state. In addition, two CdTe solar cells with identical initial performance were subjected to 32 mm static bending test for 168 hours, the results showed excellent uniformity and stability and no significant variation on J-V parameters was observed. External quantum efficiency and capacitance voltage measurements were performed and showed no significant change in spectral response or carrier concentration. Residual stress analysis showed that no additional strain was induced within the film after the bending test and that the overall strain was low. This has demonstrated the feasibility of using CdTe solar cells on UTG in new applications, when a curved module is required without compromising performance.
关键词： Ultra-thin glass,Thin films,Metalorganic chemical vapor deposition,CdTe solar cells,Bending test
更新于2025-09-19 17:13:59
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Bifunctional Ultrathin PCBM Enables Passivated Trap States and Cascaded Energy Level toward Efficient Inverted Perovskite Solar Cells
摘要： Inverted perovskite solar cells (PSCs) with C60 framework are known for their common drawback of low power conversion efficiency (PCE) < 20% because of non-radiative recombination and inefficient charge transport at their perovskite interfaces. Here, we report an ultra-thin [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as a cap layer on perovskite films to overcome this issue. Such a functional cap layer efficiently passivates trap states and establishes a gradient energy level alignment onto perovskite, facilitating the efficient charge transfer and extraction. The as-fabricated inverted PSCs capped with such ultra-thin PCBM exhibit a record PCE of 20.07%. After the storage under N2 atmosphere for more than 500 hours, the PCE of PSCs retains over 85% of its initial level. Our work provides an effective method to upgrade inverted PSCs with the C60 framework with improved efficiency and stability.
关键词： Defect passivation,Cascaded energy level,Interface Engineering,Inverted Perovskite solar cell,Ultra-thin PCBM,High efficiency
更新于2025-09-19 17:13:59
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Random nanohole arrays and its application to crystalline Si thin foils produced by proton induced exfoliation for solar cells
摘要： We report high efficiency cell processing technologies for the ultra-thin Si solar cells based on crystalline Si thin foils (below a 50 μm thickness) produced by the proton implant exfoliation (PIE) technique. Shallow textures of submicrometer scale is essential for effective light trapping in crystalline Si thin foil based solar cells. In this study, we report the fabrication process of random Si nanohole arrays of ellipsoids by a facile way using low melting point metal nanoparticles of indium which were vacuum-deposited and dewetted spontaneously at room temperature. Combination of dry and wet etch processes with indium nanoparticles as etch masks enables the fabrication of random Si nanohole arrays of an ellipsoidal shape. The optimized etching processes led to effective light trapping nanostructures comparable to conventional micro-pyramids. We also developed the laser fired contact (LFC) process especially suitable for crystalline Si thin foil based PERC solar cells. The laser processing parameters were optimized to obtain a shallow LFC contact in conjunction with a low contact resistance. Lastly, we applied the random Si nanohole arrays and the LFC process to the crystalline Si thin foils (a 48 μm thickness) produced by the PIE technique and achieved the best efficiency of 17.1% while the planar PERC solar cell without the Si nanohole arrays exhibit 15.6%. Also, we demonstrate the ultra-thin wafer is bendable to have a 16 mm critical bending radius.
关键词： proton implant exfoliation,random Si nanohole arrays,PERC solar cells,ultra-thin Si solar cells,light trapping,laser fired contact
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Miramar Beach, FL, USA (2019.8.19-2019.8.21)] 2019 IEEE Research and Applications of Photonics in Defense Conference (RAPID) - Ultra-Thin MSM Photodetectors with Nano-Structured Surface
摘要： The photon trapping structure helps to enhance the quantum efficiency (QE) in ultra-thin metal-semiconductor-metal (MSM) photodetectors so that they can achieve high speed while maintaining less than 1 micron thickness. The study shows that the short pulse response is shorter if the device is thinner. For the thin layer of Si with thickness 250nm the pulse response is 2ps, while for 400nm and 700nm the pulse responses are 3ps and 5ps, respectively. The QE for the thin layer of Si with nano-holes is higher than the flat Si with the same thickness. The QE for 250nm Si with nano-holes is 60% at 850nm wavelength, while for flat Si with the same thickness is 20%. The QE for 400nm Si with nano-holes is 80% at 850nm wavelength, while for flat Si with the same thickness is 40%. The QE for 700nm Si with nano-holes is 90% at 850nm wavelength, while for flat Si with the same thickness is 60%. The QE for 1500nm Si with nano-holes is 95% at 850nm wavelength, while for flat Si with the same thickness is 80%. The QE for the thin layer of Si with nano-holes is higher than the flat Si with the same thickness. The QE for 250nm Si with nano-holes is 60% at 850nm wavelength, while for flat Si with the same thickness is 20%. The QE for 400nm Si with nano-holes is 80% at 850nm wavelength, while for flat Si with the same thickness is 40%. The QE for 700nm Si with nano-holes is 90% at 850nm wavelength, while for flat Si with the same thickness is 60%. The QE for 1500nm Si with nano-holes is 95% at 850nm wavelength, while for flat Si with the same thickness is 80%.
关键词： MSM photodetectors,ultra-thin,quantum efficiency,nano-holes,photon trapping
更新于2025-09-16 10:30:52
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A facile light‐trapping approach for ultrathin GaAs solar cells using wet chemical etching
摘要： Thinning down the absorber layer of GaAs solar cells can reduce their cost and improve their radiation hardness, which is important for space applications. However, the lighttrapping schemes necessary to achieve high absorptance in these cells can be experimentally challenging or introduce various parasitic losses. In this work, a facile lighttrapping approach based on wet chemical etching is demonstrated. The rear‐side contact layer of ultrathin GaAs solar cells is wet‐chemically textured in between local Ohmic contact points using an NaOH‐based etchant. The resulting contact layer morphology is characterized using atomic force microscopy and scanning electron miscroscopy. High broadband diffuse reflectance and haze factors are measured on bare and Ag‐coated textured contact layers. The textured contact layer is successfully integrated as a diffusive rear mirror in thin‐film solar cells comprising a 300‐nm GaAs absorber and Ag rear contact. Consistent increases in short‐circuit current density (JSC) of approximately 3 mA cm?2 (15%) are achieved in the textured cells, while the open‐circuit voltages and fill factors do not suffer from the textured rear mirror. The best cell achieves a JSC of 24.8 mA cm?2 and a power conversion efficiency of 21.4%. The textured rear mirror enhances outcoupling of luminescence at open circuit, leading to a strong increase in the external luminescent efficiency.
关键词： ultra‐thin GaAs,wet etching,textured III‐V solar cells,light trapping,luminescence outcoupling
更新于2025-09-12 10:27:22