Fully High‐Temperature‐Processed SnO2 as Blocking Layer and Scaffold for Efficient, Stable, and Hysteresis‐Free Mesoporous Perovskite Solar Cells.

Abstract: Planar perovskite solar cells (PSCs) based on low‐temperature‐processed (LTP) SnO2 have demonstrated excellent photovoltaic properties duo to the high electron mobility, wide bandgap, and suitable band energy alignment of LTP SnO2. However, planar PSCs or mesoporous (mp) PSCs based on high‐temperature‐processed (HTP) SnO2 show much degraded performance. Here, a new strategy with fully HTP Mg‐doped quantum dot SnO2 as blocking layer (bl) and a quite thin SnO2 nanoparticle as mp layer are developed. The performances of both planar and mp PSCs has been greatly improved. The use of Mg‐SnO2 in planar PSCs yields a high‐stabilized power conversion efficiency (PCE) of close to 17%. The champion of mp cells exhibits hysteresis free and stable performance with a high‐stabilized PCE of 19.12%. The inclusion of thin mp SnO2 in PSCs not only plays a role of an energy bridge, facilitating electrons transfer from perovskite to SnO2 bl, but also enhances the contact area of SnO2 with perovskite absorber. Impedance analysis suggests that the thin mp layer is an “active scaffold” selectively collecting electrons from perovskite and can eliminate hysteresis and effectively suppress recombination. This is an inspiring advance toward high‐performance PSCs with HTP mp SnO2. [ABSTRACT FROM AUTHOR]