Enhancing Performances of Perovskite Solar Cells by Using Zinc Oxide Quantum Dots/Mesoporous Titania Electron Transport Layer

As the photovoltaic performance of mesoscopic perovskite solar cells (PSCs) is strongly dependent on the interface between perovskite and electron transport layer. Herein, an attempt to load facile processed ZnO quantum dots (ZQDs) or TiO2 quantum dots (TQDs) into the mp-TiO2 layer via a simple spin-coating method was first performed. Both of them had huge impact on the morphology of perovskite films, leading to larger perovskite grains. However, the power conversion efficiency (PCE) of these two kinds of QDs modified cells exhibited a different tendency. The champion PCE of ZQDs modified PSCs was remarkably improved from 14.54% to 17.2%, while that of TQDs modified ones decreased to 11.78%. We demonstrated that the enhanced PCE and short-circuit current (Jsc) were attributed to the enlarged grain size and enhanced light absorption of perovskite film, faster electron extraction and transport as well as less recombination for ZQDs modified PSCs, which mainly resulted from the increased active specific surface area. On the contrary, deterioration of TQDs modified PSCs was exactly ascribed to the aggregation of TQDs which sharply decreased the specific surface area of the electron transport layer. The current work provided an efficient and facile way to improve the photovoltaic performance of mesoscopic PSCs.