(Invited) InGaN/GaN Multiple Quantum Well Solar Cells for Energy and Hydrogen Generation

Abstract

InGaN alloys are promising for solar cells and solar water splitting because they have direct bandgaps that cover almost the whole solar spectrum. This paper provides a brief overview on recent advances made by our group in the area of III-nitrides for energy and hydrogen generation. Solar cells based on InxGa1-xN/GaN (x∼0.35) multiple quantum well (MQW) structures have been fabricated and were shown exhibit an open circuit voltage (Voc) of 1.80 V, short circuit current density (Jsc) of 2.5 mA/cm2 and a solar-energy-to-electricity conversion efficiency (η) of 2.95% under the irradiation by a simulated sunlight (AM 1.5 G, 1-sun,100 mW/cm2). Under the irradiation of concentrated sunlight, Voc, Jsc and η were found to increase with solar concentration. Furthermore, InGaN/GaN MQW solar cells were effectively monolithic solar-photoelectrochemical cells which are capable to directly generate hydrogen gas under zero bias via solar watersplitting. Under the irradiation of 1 sun (AM 1.5 G), a 1.5% solar to-fuel conversion efficiency has been achieved under zero bias with an excellent chemical stability.