One-step hydrothermal synthesis of Zr-doped brookite TiO2 nanorods for highly efficient perovskite solar cells

Perovskite solar cells (PSCs) fabricated of TiO2 electron transporting material (ETM) have aroused tremendous attention, but their power conversion efficiency (PCE) needs further improvements. In this study, for the first time, zirconium (Zr)-doped brookite TiO2 nanorods (ZTO) are synthesized by a facile route and subsequently employed as an ETM in PSCs which finally achieves a considerable PCE of 19.42 % by optimizing all operating conditions. Further characterizations have been undertaken to explore in detail the effects of Zr doping on the nature of the perovskite active layer and the photovoltaic performance. As a consequence, the enhanced PCE can be ascribed to the high quality perovskite crystals and a more favorable energy level alignment between the perovskite layer and ZTO mesoporous layer.