InGaN/GaN multiple quantum well solar cells for energy and hydrogen generation

摘要

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 In_xGa_(1-x)N/GaN (x～0.35) multiple quantum well (MQW) structures have been fabricated and were shown exhibit an open circuit voltage (V_(oc)) of 1.80 V, short circuit current density (J_(sc)) of 2.5 mA/cm~2 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/cm~2). Under the irradiation of concentrated sunlight, V_(oc), J_(sc) 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 water splitting. 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.