Analytical modelling and performance study of single-junction GaAs-based solar cell efficiency

Abstract

The main objective of this study is to fabricate a control (a standard single-junction solar cell grown straight on bare GaAs substrate) and flexible freestanding GaAs-based single-junction solar cells (grown on a graphene layer deposited on GaAs substrate). Besides, the research work aims to characterise and mathematically simulate the PV cell behaviour using COMSOL Multiphysics (version 6). The control PV cell, as a baseline for comparison, was epitaxially grown by metal–organic chemical vapour deposition (MOCVD). Whilst remote epitaxy technique in addition to the ‘MOCVD’ method was used to fabricate the flexible freestanding GaAs solar cells. Remote epitaxy technique was employed to reduce the cost of the expensive monocrystalline GaAs substrate and produce flexible solar cells. The electrical properties of the membranes, including the current–voltage (I–V) curve, dark current, and quantum efficiency, were measured experimentally to evaluate how new flexible membranes perform relative to the control (traditional PV cell). The results showed that the power conversion efficiency of the fabricated single-junction GaAs membranes was about 9% at air mass condition AM1.5 (1000 W/m² insolation and 25 °C). Therefore, a mathematical simulation by COMSOL and a design of experiment by Minitab were proposed to improve their efficiency. The efficiency of the fabricated GaAs solar cells was enhanced to 19.62% by optimising the layer thickness and doping. Furthermore, the (I–V) curve, dark current, and quantum efficiency of the control solar cell as a benchmark for the flexible membrane were analysed by COMSOL Multiphysics/Semiconductor physics to compare with the experimental measurements.