Efficiency Improvement of Single-Junction In(0.5)Ga(0.5)P Solar Cell with Compositional Grading p-Emitter/Window Capping Configuration

Abstract

In this study a novel p-emitter/window capping configuration design applied to a p(+)-n In(0.5)Ga(0.5)P solar cell is developed. By grading the Ga and Al compositions in the interface between the p-In(0.5)Ga(0.5)P emitter and p-In(0.5)Al(0.5)P window layers, the output characteristics of the p(+)-n In(0.5)Ga(0.5)P solar cell are improved. It is found that the photoluminescence (PL) intensity is increased and the minority carrier lifetime obtained from room-temperature time-resolved (TR) PL measurement can be increased from 5.3 ns of the typical design to 7.0 ns, indicating that the application of compositional grading can improve crystal quality and the interface becomes smoother, thus reducing the nonradiative recombination losses. Both the short-circuit current and open-circuit voltage are increased correspondingly and the conversion efficiency is improved from 14.57% of the typical design to 15.32% of the new p-emitter/window configuration under one-sun air-mass 1.5 global illumination. (C) 2010 The Japan Society of Applied Physics