Comparison of various InGaAs-based solar cells for concentrated photovoltaics applications

Abstract

. InGaAs lattice matched to InP is a promising material for bottom sub-cell in a 4-junction solar cell designed for concentrated photovoltaics applications. Here we compare the performances of two structures that could replace standard monolithic InGaAs homojuntion. The first one is a stand-alone solar cell realized via epitaxial lift-off (ELO) process on a flexible substrate. The second one is a heterojunction solar cell, kept on its parent InP substrate, composed of an InP emitter and an InGaAs absorber. A third structure made of an homojunction InGaAs solar cell on an InP substrate is used as reference. Under one sun illumination the heterojunction solar cell shows the highest V OC (383 mV) and fill factor. Nevertheless, when performing under concentrated sunlight the structure is limited by a lower V OC increase rate and a high series resistance compared to the ELO cell. Indeed, ELO cell shows a lower V OC (353 mV) than the two other structures under one sun illumination but, when performing under concentration, ELO cell recovers V OC and shows a lower impact of series resistance. Therefore, both ELO and heterojunction solar cell show interesting and complementary behaviors that could be interesting to associate in an ELO-heterojunction solar cell.