The influence of perpendicular transport behavior on the properties of n-i-p type amorphous silicon solar cells

Abstract

Different types of boron-doped window layers have been prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) at a low temperature of 150°C. The effects of perpendicular transport behavior on the properties of n–i–p type amorphous silicon (a-Si) solar cells, which involve inner perpendicular conductivity of p layers, perpendicular transport properties at p/ITO interfaces and recombination kinetics at i/p interfaces have been investigated by perpendicular dark conductivity, potential barrier at p/ITO and dark current–voltage characteristics of n-i-p a-Si diodes, respectively. High doping efficiency in the window layers with nano-sized silicon crystals has been observed to facilitate the significant improvement of perpendicular dark conductivity and transport behavior at p/ITO interfaces. The dark current–voltage characteristics indicated intrinsic a-Si/p-type microcrystalline silicon heterojunction transitions possessed much higher recombination rate and decreased value of built-in potential in the intrinsic layer. By optimizing the process parameters, high open circuit voltage (0.96V) and fill factor (0.73) were achieved for n-i-p type a-Si single junction solar cell with p-type amorphous silicon carbide/nanocrystalline silicon hybrid window layer.