Preparation of Back-Contact PEDOT:PSS/c-Si Heterojunction Solar Cells by a Solution Method and Their Performance Optimization

Enhancing the power conversion efficiency (PCE) of solar cells remains a critical challenge for the rapidly advancing photovoltaic industry. To explore low-cost fabrication methods, this study employed solution processing to fabricate back-contact (BC) poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/crystalline silicon (c-Si) heterojunction solar cells. The geometry of the back electrode was optimized by systematically varying the aluminum (Al) finger width and the width ratio between the Al fingers and the PEDOT:PSS hole transport layer (HTL), aiming to improve the PCE. This approach provides valuable perspectives for enhancing the BC solar cell efficiency while reducing manufacturing costs. Using shadow masks with gradient variations in the Al finger width and finger-to-HTL width ratio, Al cathodes with corresponding geometries were deposited via thermal evaporation onto n-Si substrates. The resulting BC solar cells were precisely characterized to elucidate the influence of back electrode geometry on the device performance. Optimization of the finger width and width ratio yielded an optimal geometry configuration with an Al finger width of 250 μm and a finger-to-HTL width ratio of 3.5:1, ultimately achieving a champion device efficiency of 15.43%.