Low Temperature Processed Highly Efficient Hole-Transport-Layer Free Carbon-based Planar Perovskite Solar Cells with SnO2 Quantum Dot Electron-Transport-Layer

Abstract The use of expensive hole transport layer (HTL) and back contact along with the stability issue of perovskite solar cells have been a detrimental factor when it comes to commercialization of the technology. In addition, high-temperature and long annealing time processed electron transport layers (ETLs, e.g., TiO2) prevents the flexible solar cell application in most polymer substrate. Herein, we opted for HTL-free carbon electrodes owing to their low-cost production and superior stability in air, compared to their noble metal counterparts. In this work, we fabricate planar perovskite solar cells using low-temperature solution processed SnO2 quantum dots (QDs) as ETL, which offers significant advantages over high temperature processed ETLs due to its excellent electron extraction and hole blocking ability. In addition, by integrating a low cost and stable carbon electrode, an impressive energy conversion efficiency of 13.64% with a device architecture glass/In doped SnO2/QD-SnO2/Perovskite/Carbon under 1 sun illumination at ambient conditions have been achieved. This work paves the way to achieve fully low-temperature processed printable perovskite solar cells (PSCs) at an affordable cost by integrating the QD SnO2 ETL and Carbon electrode.