Improved Infrared Light Management with Transparent Conductive Oxide/Amorphous Silicon Back Reflector in High‐Efficiency Silicon Heterojunction Solar Cells

Abstract

To improve the infrared (IR) response, a high‐refractive‐index intrinsic amorphous silicon (a‐Si:H) layer is introduced after metallization of bifacial silicon heterojunction (SHJ) solar cells, resulting in a transparent conductive oxide (TCO)/a‐Si:H back reflector, which functions like distributed Bragg reflector (DBR). This concept is demonstrated by both Sentaurus Technology Computer‐Aided Design (TCAD) simulation and experimental methods. The TCO/a‐Si:H back reflector can increase rear internal reflectance by reducing the transmission loss, thus improving the IR external quantum efficiency. The using of Sn‐doped In2O3 (ITO)/a‐Si:H back reflector in >23.5% efficiency SHJ solar cells can improve short‐circuit current density by 0.4 mA cm−2 which is quite similar as using the more expensive ITO/Ag back reflector, while keeping a cell bifaciality of 55%. This brings its advantage for monofacial application case. Future studies would be nice to work on higher transparent back reflectors to broaden the application in bifacial case. This back‐reflector design promotes IR response of SHJ solar cells with transferring to a wide variety of TCOs.