Efficiency enhancement of InN quantum dot based solar cell

Abstract

A fundamental limitation in achieving ultra-high efficiency solar cells (> 60%) is the availability of materials and corresponding device structures. The InGaN material system offer substantial potential in developing ultra-high efficiency devices, both because of measurements indicating that the band gap on InN is lower than previously though and also due to other unique material properties, such as the strong polarization and affiliation piezoelectric effects. Several key issues remain, including p-type doping, which substrates to use, and the material quality of the layers. Results show that the material quality of existing films allows a 5 stack tandem at 500X to approach 60%. Results also show InN grown on Ge with a crystalline Al interlayer, which could be used to replace a tunnel contact. High band gap GaN p-i-n and InGaN/GaN quantum dot solar cells show good spectral response and Voc > 2V.