Efficiency of GaN/InGaN double-heterojunction photovoltaic cells under concentrated illumination

In this study, GaN/InGaN double-heterojunction (DH) photovoltaic (PV) devices were fabricated and their theoretical PV properties were simulated. When the characteristics of PV devices were compared between illumination conditions of one sun and 120 suns, the PV properties – open-circuit voltage, short-circuit current density, and filling factor – measured in fabricated GaN/InGaN PV devices improved more than those calculated from the simulation. This result could be tentatively attributed to the trap-filling effect under a high injection density of photo-generated carriers, which would relatively reduce the series resistance and increase the shunt resistance. The improvements in the conversion efficiencies of the GaN/InGaN PV devices between illumination conditions of one sun and 120 suns were 4.6% and 70.8% for simulated and measured conversion efficiencies, respectively. The differences between the simulated results and measurements of actual GaN/InGaN PV devices are consistent.