A Low-Temperature, Solution Processable Tin Oxide Electron-Transporting Layer Prepared by the Dual-Fuel Combustion Method for Efficient Perovskite Solar Cells

Although tin oxide (SnO₂) has been employed recently as an efficient electron-transporter to realize highly efficient organometal halide perovskite solar cells (PVSCs), it is still quite challenging to apply it through facile solution-based synthesis at low enough temperature (<150 °C) to be compatible with the roll-to-roll printing on polymer substrates. In this work, a dual-fuel combustion method has been successfully adapted to modulate the exothermic characteristics and processing temperature (140 °C) of SnO₂ to achieve homogeneous and crystalline thin film as efficient electron-transporting layer for PVSCs. The fabricated SnO₂ film not only has high transparency (from 350 nm to near-infrared region) but also possesses good electron extraction ability, as evidenced by the efficient PL quenching in bilayered SnO₂/CH₃NH₃PbI₃ film. By passivating SnO₂ surface with a C₆₀-containing self-assembled monolayer (C₆₀-SAM), a high power conversion efficiency (PCE_max) of >15% with negligible hysteresis can be achieved in PVSC. This demonstrates the great potential of applying this dual-fuel combustion process to improve processability and charge-transporting properties of metal oxides for organic electronics applications.