Photon Management for Efficient and Stable Large-Area Perovskite Solar Cells via Luminescent Thin Films of Platinum(II) Complex

As a representative photon management strategy converting high-energy photons into low-energy ones, photon downshifting in photovoltaic applications can be realized by introducing strongly luminescent materials that are properly designed to have spectral overlap with the corresponding light absorbers. Especially for perovskite solar cells (PSCs), photon downshifting has been suggested as an effective way to overcome UV-related problems such as exciton loss, thermalization, and catalytic decomposition of the photoactive layers. However, it is still challenging to achieve thin-film photon downshifting layers (PDLs) with high photoluminescence quantum yields (PLQYs) and versatility for fabrication, considering upcoming high-performance and large-area PSCs.<br/>Herein, to enhance UV stability without any loss in photocurrent generation, a highly blue-emissive Pt(II) complex is developed for effective photon management in high-performance PSCs. Thin PDLs based on the Pt(II) complex are fabricated on glass substrates of PSCs using ultrasonic spray deposition, leading to significant improvement in PLQY and facile production of large-area PDLs. By introducing the PDLs, a maximum device performance of 22.03% is achieved for large-area PSCs with an active area of 25 cm². Owing to their long-range photon downshifting effect, in which absorbed UV photons are converted into visible emission, remarkable improvements in UV stability of PSCs are realized with the PDL coating. In terms of efficient photon management, luminescent thin films of UV-to-visible converting Pt(II) complex suggest wide ranging applicability that can further improve the performance and stability of other optoelectronic devices.