In_xGa_1?xN/GaN Multiple Quantum Well Solar Cells with Conversion Efficiency of 3.77%

We report on fabrication and photovoltaic characteristics of In_xGa_1?xN/GaN multiple quantum well solar cells with different indium compositions and barrier thicknesses. The as-grown samples are characterized by high-resolution x-ray diffraction and reciprocal space mapping. The results show that the sample with a thick barrier thickness (10.0 nm) and high indium composition (0.23) has better crystalline quality. In addition, the dark current density-voltage (J–V) measurement of this device shows a significant decrease of leakage current, which leads to high open-circuit voltage V_oc. Through the J–V characteristics under an Air Mass 1.5 Global (AM 1.5 G) illumination, this device exhibits a V_oc of 1.89 V, a short-circuit current density J_sc of 3.92 mA/cm² and a fill factor of 50.96%. As a result, the conversion efficiency (η) is enhanced to be 3.77% in comparison with other devices.