In this study,we report on the realization of ultraviolet response enhancement in PV cells through the structure of ITO/SiO2/np-Silicon frame(named as SINP),which was fabricated by the state of the art processing.The fabrication process consists of thermal diffusion of phosphorus element into p-type texturized crystal Si wafer,thermal deposition of an ultra-thin silicon dioxide layer(15-20) at low temperature,and subsequent deposition of thick In2O3:SnO2(ITO) layer by RF sputtering.The structure,morphology,optical and electric properties of the ITO film were characterized by XRD,SEM,UV-VIS spectrophotometer and Hall effect measurement,respectively.The results showed that ITO film possesses high quality in terms of antireflection and electrode functions.The device parameters derived from current-voltage(I-V) relationship under different conditions,spectral response and responsivity of the ultraviolet photoelectric cell with SINP configuration were analyzed in detail.We found that the main feature of our PV cell is the enhanced ultraviolet response and optoelectronic conversion.The improved short-circuit current,open-circuit voltage,and filled factor indicate that the device is promising to be developed into an ultraviolet and blue enhanced photovoltaic device in the future.
HE Bo1,MA ZhongQuan1,ZHAO Lei1,ZHANG NanSheng1,LI Feng1,SHEN Cheng1,SHEN Ling1,ZHOU ChengYue1,YU ZhengShan2 & YIN YanTing2 1 SHU-Solar E PV Laboratory,Department of Physics,Shanghai University,Shanghai 200444,China
Three kinds of methods (0.08 mol/L iodine in ethanol, SiNx:H, and 40% HF) are used to passivate solar-grade Czochralski (Cz) silicon wafers. Thereafter, minority carrier lifetime and Fe-B pair density of the wafers are measured using the microwave photo-conductance decay (μ-PCD) technique. Based on the measured minority carrier lifetime, it is found that the passivation quality achieved by 0.08 mol/L iodine in ethanol is the best, while that by 40% HF solution is the worst. For the identical wafer, the density distribution of Fe-B pairs is different when different passivation methods are used. When the wafers are passivated by SiNx:H, there exists a close correlation between the distribution of minority carrier lifetime and the concentration distribution of Fe-B pairs. Furthermore, for wafers with high-quality passivation, there is a strong correlation between the recombination center concentration and the Fe-B pair density. All the analyses verify that the surface passivation quality of wafers influences the measurement results of minority carrier lifetime, Fe-B pair density and recombination center concentration.
LI FengMA ZhongQuanMENG XiaJieLU PengYU ZhengShanHE Bo
Solar cell grade crystalline silicon with very low reflectivity has been obtained by electrochemically selective erosion.The porous silicon(PS) structure with a mixture of nano-and micro-crystals shows good antireflection properties on the surface layer, which has potential for application in commercial silicon photovoltaic devices after optimization.The morphology and reflectivity of the PS layers are easily modulated by controlling the electrochemical formation conditions(i.e., the current density and the anodization time).It has been shown that much a lower reflectivity of approximately 1.42% in the range 380-1100 nm is realized by using optimized conditions.In addition, the minority carrier lifetime of the PS after removing the phosphorus silicon layer is measured to be ～3.19 μs.These values are very close to the reflectivity and the minority carrier lifetime of Si3N4 as a passivation layer on a bulk silicon-based solar cell(0.33% and 3.03 μs, respectively).
