Multi-Quantum Well (MQW) GaAs/AlGaAs Solar Cell

Solar photovoltaic technologies have garnered an increasing amount of attention due to their relevance to developing sustainable energy systems in the future which do not harm the environment. Multiquantum well (MQW) solar cells offer a potential device structure which can improve the current generation and efficiency of conventional p-i-n junction solar cells. Typically, only photons with energies matching or exceeding that of the bandgap of a solar cell can be absorbed to convert the irradiated light into an electrical current. Photons with less energy than the bandgap are not able to excite free charge carriers, which in effect reduces the efficiency of a solar cell. Layered quantum well structures in place of the intrinsic region of a solar cell could potentially harness these lower energy photons to generate current from charge carriers confined within those quantum wells. In this study, a single-junction MQW GaAs solar cell structure using 13 GaAs/Al0.35Ga0.65As quantum wells is proposed and simulated using Crossslight APSYS (TCAD software). The structure of the quantum well region is optimized by investigating the effects of the Al0.35Ga0.65As barrier thickness and the GaAs quantum well thickness on the device performance. The optimized cell efficiency is found to be 7.636% when 50 nm quantum wells and 1 nm barriers are used. This performance provides insights into how tunneling can reduce the performance of a MQW from its maximum theoretical efficiency and the trade-off between the thickness of the barriers and wells to design an optimal solar cell configuration.