Numerical analysis of amorphous silicon solar cells: a detailed investigation of the effects of internal field distribution on cell characteristics

This paper describes the application of a new iterative method to numerical calculation of the performance of amorphous silicon p-i-n solar cells. Using this method, the effects of gap-state density, dopant impurities (B and P), and various cell parameters (diffusion length, interface recombination velocities, thickness of the i layer, etc.) on cell characteristics are investigated. The calculated results show that a strong electric field advantageously effects cell characteristics (especially through fill factor) in the i-layer where many photocarriers are generated. However, a uniform field isn’t always adequate for high conversion efficiency. The improvement in conversion efficiency provided by boron doping is attributed to stretching of the diffusion length rather than rearrangement of the field distribution.