High performance thin quantum barrier InGaN/GaN solar cells on sapphire and bulk (0001) GaN substrates

We demonstrate high performance InGaN/GaN multiple quantum well solar cells with thin quantum barriers and spectral response extending to 460 nm. Devices grown on bulk (0001) GaN substrates with up to 50 quantum wells (QWs) outperform those grown simultaneously on sapphire due to the lower threading dislocation density. Increasing the number of QWs eventually leads to performance degradation of devices grown on both substrates. Solar cells are demonstrated with peak external quantum efficiencies up to 60%, open circuit voltages up to 2.28 V, fill factors up to 80%, and conversion efficiencies up to 2.4% under 1 sun AM0 equivalent illumination.