Design and Simulation of Multiquantum-Well AlGaAs/GaAs Single Junction Solar Cell with Back Surface Reflector

Abstract

This paper reports on the design and simulation of a multiquantum Well (MQW) AlGaAs/GaAs single p-i-n junction cell with a Distributed Bragg Reflector (DBR) placed at back surface. The DBR structure reflects the part of the spectrum that benefits from absorption in the AlGaAs MQW structure, while being transparent to the IR spectrum. The addition of a DBR allows for a possible second bottom cell junction to be placed beneath the DBR in series with the MQW single cell for an additional efficiency enhancement. The efficiencies and short-circuit currents for the AlGaAs MQW cell with and without DBR are simulated. An energy balance equations model coupled with drift-diffusion equations is solved in heterojunction p-i-n with embedded quantum wells to model hot electron effects. The current-voltage characteristics of an MQW single junction AlGaAs/GaAs p-i-n solar cell structure were compared with measured data. The efficiencies and short-circuit currents of an optimized cell with and without DBR are simulated. Results obtained show improvement in short circuit current and efficiency when both MQW and DBR were used. Simulation results predict an efficiency of about 28.4% for the MQW AlGaAs-DBR single p-i-n junction photovoltaic cell under the presence of both radiative and nonradiative recombination mechanisms.