Rapid Vapor-Phase Deposition of High-Mobility p-Type Buffer Layers on Perovskite Photovoltaics for Efficient Semitransparent Devices

Perovskite solar cells (PSCs) with transparent electrodes can be integrated with existing solar panels in tandem configurations to increase the power conversion efficiency. A critical layer in semitransparent PSCs is the inorganic buffer layer, which protects the PSC against damage when the transparent electrode is sputtered on top. The development of n-i-p structured semitransparent PSCs has been hampered by the lack of suitable p-type buffer layers. In this work, we develop a p-type CuOx buffer layer, which can be grown uniformly over the perovskite device without damaging the perovskite or organic hole transport layers. The CuOx layer has a high hole mobility (4.3 ± 2 cm2 V–1 s–1), a high transmittance (>95%), and a suitable ionization potential for hole extraction (5.3 ± 0.2 eV). Semitransparent PSCs with efficiencies of up to 16.7% are achieved using the CuOx buffer layer. Our work demonstrates a new approach for integrating n-i-p structured PSCs into tandem configurations, as well as enabling the development of other devices that need high-quality, protective p-type layers.