Efficiency enhancement for resonant-cavity-enhanced InGaN/GaN multiple quantum well solar cells

We proposed a new approach of enhancing the quantum efficiency of InGaN/GaN multiple quantum well (MQW) solar cells using resonant cavity in this study. The resonant-cavity-enhanced (RCE) structure is designed with a top mirror and bottom distributed Bragg reflector (DBR). The origin of the enhancement in quantum efficiency was the resonance-induced increase of the optical field, which caused more photons to be absorbed in the InGaN absorption layers. We simulated the photovoltaic performance of InGaN/GaN MQW solar cells by comparing RCE-type and conventional solar cells. The best structural parameters are estimated to be 600 nm for cavity length, 10% for the reflectivity of top mirror and as high as possible for the reflectivity of bottom DBR (in simulation we used 99%). As a result, the RCE-type InGaN/GaN MQW solar cell shows an enhancement in short-circuit current density by 2.12 times and conversion efficiency by 2.13 times, as compared to those of a conventional InGaN/GaN MQW solar cell.