Fabrication of Water-Repellent Platinum(II) Complex-Based Photon Downshifting Layers for Perovskite Solar Cells by Ultrasonic Spray Deposition

Despite a rapid increase in light harvesting efficiencies, organic-inorganic hybrid perovskite solar cells (PSCs) exhibit relatively inefficient photocurrent generation in the UV region and severe degradation when exposed to UV light and humidity. Herein, to enhance UV and humidity stability as well as photocurrent generating efficiency, a water-repellent platinum(II) complex,Pt-F, is developed as a luminescent photon downshifting layer (PDL) for PSCs. ThePt-FPDL is fabricated on the glass substrate of a PSC using ultrasonic spray deposition, resulting in a considerably higher crystallinity and photoluminescence quantum yield (PLQY) than those fabricated by conventional spin-coating processes (PLQYs of 77% and 19%, respectively). A maximum device performance of 22.0% is achieved through the addition of a PDL coating to a 21.4% efficient PSC owing to the long-range photon downshifting effect ofPt-F, as confirmed by the enhanced spectral response of the device in the UV region. Moreover, remarkable improvements in UV and humidity stability are observed inPt-F-coated PSCs. The versatile effects of thePt-F-based PDL, when fabricated by ultrasonic spray deposition, suggest wide ranging applicability that can improve the performance and stability of other optoelectronic devices.