High-Performance, Air-Stable, Low-Temperature Processed Semitransparent Perovskite Solar Cells Enabled by Atomic Layer Deposition

We demonstrate high-performance, air-stable, low-temperature processed (≤100 °C) semitransparent (ST) perovskite solar cells (PSCs) by the applications of atomic layer deposition (ALD) technology to deposit ZnO and Al₂O₃ films as cathode buffer layer (CBL) and encapsulation layer, respectively. The application of ALD ZnO film as CBL in PSCs delivers several remarkable features, including fine-tunability of the work function of the electrode, low deposition temperature (80 °C), high charge selectivity, good electron-transporting ability (filed-effect mobility = 16.1 cm² V^–1 s^–1), and excellent film coverage. With these desired interfacial properties, the device with opaque Ag electrode delivers high power conversion efficiency (PCE) up to 16.5%, greatly outperforming the device with state-of-the-art CBL ZnO nanoparticles film (10.8%). For ST PSCs employing Ag nanowires as transparent top electrode, a remarkable PCE of 10.8% with a corresponding average visible transmittance (AVT) of 25.5% is demonstrated, which represents the highest PCE ever reported for ST PSCs with similar AVT. More significantly, the insufficient ambient stability of ST device is significantly improved by employing excellent gas-barrier performance of ALD Al₂O₃-based encapsulation layer with an oxygen transmission rate of 1.9 × 10^–3 cm³ m^–2 day^–1 and a water vapor transmittance rate of 9.0 × 10^–4 g m^–2 day<sup>–1