Technology Outline (Process Description)

The research activity at Photovoltaics lab, at IIT Madras focusses on fabricating silicon heterojunction (SHJ) solar cells and developing it further to make a two terminal stacked tandem cell by series integrating a metal halide perovskite as top cell. The processing is at temperatures completely below 200 ^oC (unlike the conventional high temperature processing of silicon bases devices). To that end, (very high frequency) plasma (PECVD) and atomic layers deposition (ALD) processes are developed and employed for growing multiple layered stacks consisting of ETL, HTL, Passivation and TCO layers on textured silicon wafers. To increase the temperature window of cell processing and stability of carrier life time, the SHJ deposition scheme is adapted to make carrier selecting contact (CSC) solar cells, replacing the amorphous silicon layers with metal oxide layers. The static deposition technology is transferred to the dynamic deposition inline tool at BHEL, ASSEP Gurgaon to fabricate 5’x5’ SHJ solar cells.