Full‐Spectral Response Perovskite Solar Cells Through Integration of MXene Modified Near‐Infrared Organic Heterojunction and Waveguide‐Structure Quantum‐Cutting Down‐Converter

Abstract To date, lead‐based perovskite solar cells (PSCs) are optimized to the extreme and achieved an efficiency of as much as 26.1%. Expanding the spectral response is one of the most effective methods for achieving further efficiency breakthroughs. In this study, integrated PSCs are constructed by combining near‐infrared (NIR) organic bulk heterojunctions (BHJs) with perovskite layers to broaden the NIR spectral response range. Ultraviolet (UV)‐plasma‐treated MXene Nb 2 CT x ‐ quantum dots (QDs) are introduced to promote exciton dissociation inside the BHJ and to solve the problems of severe nonradiative exciton recombination and open‐circuit voltage ( V oc ) loss in IPSCs. In addition, CsPbCl 3 :Yb(7%),Li(2%) QDs with quantum‐cutting emission and photoluminescence quantum yield of up to 170% act as down‐converters to enhance the utilization of UV light. MgF 2 is deposited on the quantum‐cutting layer to construct a waveguide‐structured anti‐reflection layer and further increase UV photon utilization. The champion device achieves superior photoelectric performance with a photoelectric conversion efficiency of 24.3%, V oc of 1.17 V, a short circuit current of 26.65 mA cm −2 , and a fill factor of 77.95%. Champion devices exhibit excellent UV and long‐term stability. This study provides an instructive strategy for fabricating high‐performance full‐spectral‐response PSCs.