Optimization of High-Efficiency n+-p-p+ Back-Surface-Field Silicon Solar Cells

Abstract

High-efficiency silicon solar cells are fabricated with back-surface-field (BSF) structures using medium-resistivity, float-zone substrates. The cell processes are optimized using a new BSF process in order to maintain a high minority-carrier lifetime. In addition, they are improved with a passivated, V-grooved surface to enhance collection efficiency. The resultant cells exhibit conversion efficiencies of 19.1% with a short-circuit current density of 38.4 mA/cm². The minority-carrier lifetime and surface recombination velocity are estimated to be 341 µs and 3×10⁵ cm/s using a computer program.