p-Type Single-Wall Garbon Nanotube Network on n-Type Si for Heterojunction Photovoltaic Cells
Z. Li, Y. Xu, V. Saini, E. Dervishi, M. Mahmood, A.R. Biris, A.S. Biris
University of Arkansas at Little Rock, US
Keywords: heterojunction photovoltaic cells, SWNT, n-Type Si
Abstract:The solar cells based on high-density p-n heterojunctions between single wall carbon nanotubes (SWNTs) and n-type crystalline silicon were produced with airbrushing technique. The SWNTs/n-Si heterojunction is rectifying. Under optical excitation the numerous heterojunctions formed between the semitransparent SWNTs thin coating and the n-type silicon substrate generate electron-hole pairs, which are then split and transported through SWNTs (holes) and n-Si (electrons), respectively. The nanotubes serve as both photogeneration sites and a charge carriers collecting and transport layer. It was also found that the thionyl chloride (SOCl2)-treatment of SWNT coating films can lead to a significant increase in the conversion efficiency through re-adjusting the Fermi level and increasing the carrier concentration and mobility of the nanotube network. Initial tests have shown a power conversion efficiency of above 3%, proving that SOCl2 treated-SWNTs/n-Si is a potentially suitable configuration for making solar cells.