See‐Through Flexible Photovoltaic Modules of Ultrathin Silicon Solar Microcells Enhanced by Synergistic Luminescent and Reflective Near‐Infrared Backplanes

Abstract

Ultrathin single‐crystalline silicon solar microcells assembled into see‐through and flexible modules have exhibited broadly applicable cost‐effective photovoltaics with reliable durability and efficiency. However, their module output power has suffered from inherent limitations caused by the inferior photon absorption property and the inactive see‐through windows. Herein a strategy is presented to enhance the performance of see‐through flexible ultrathin silicon microcell modules by employing visibly transparent but near‐infrared‐manipulatable optical backplanes, such as a luminescent waveguide gathering near‐infrared photons and a backside reflector mitigating near‐infrared photon escape. Simultaneous integration of these near‐infrared backplanes provides more photovoltaic gains to silicon solar modules than the sum of each backplane capability, and this synergy is due to the promoted properties of the photoluminescence process and waveguiding. The experimental module with ≈3‐µm thick silicon solar microcells can achieve up to ≈40%‐boosted output power generation when assisted by these backplanes. Detailed studies of optical and photovoltaic characterizations for near‐infrared backplanes and their integration modules elucidate the effectiveness of designed backplanes for see‐through flexible silicon photovoltaics.