Impact of using dual back surface field layers of different materials on GaAs single junction solar cell performance

Abstract

This research aspires to investigate the impact of employing dual BSF layers on the performance of single junction GaAs solar cells using the Silvaco TCAD simulator. A layer of GaAs, InGaP, and InAlGaP has been implemented as a second BSF layer on top of the original BSF layer of the n-InGaP/n-GaAs/p-GaAs/p-InAlGaP structured solar cell. The results show that using GaAs as a second BSF layer has increased the carrier’s recombination and degraded the cell efficiency due to its lower energy bandgap, which creates a potential well that lessens the number of photogenerated carriers flowing through the conduction band toward electrodes. However, adding InGaP and InAlGaP as a second BSF layer decreases the recombination rate and generates a broad electric field region leading to extra photogenerated carriers drifting through the cell, which increases the efficiency from 29.42% to 29.81% for the case of using InGaP and 30.33% for the case of using InAlGaP. Furthermore, increasing the thickness and doping of the second BSF layer reduces the carriers’ recombination at the boundaries of this layer, which implies efficiency enhancement.