Tuning of perovskite solar cell performance via low-temperature brookite scaffolds surface modifications

摘要

The nature of metal oxide scaffold played a pivotal role for the growth of high quality perovskites and subsequently facilitates efficient photovoltaics devices. We demonstrate an effective way to fabricate a low-temperature TiO₂ brookite scaffold layer with a uniform and pinhole-free layer for enhancing photovoltaic properties of perovskite solar cells. Various concentrations of TiCl₄ were used to modify brookite TiO₂ for efficient charge generation and fast charge extraction. We observed that the brookite layer with an appropriate TiCl₄ treatment possesses a smooth surface with full coverage of the substrates, whereas TiCl₄ treatment further improves the contact of the TiO₂/perovskite interface which facilitates charge extraction and drastically influenced charge recombination. The surface treated brookite scaffolds perovskite devices showed an improved performance with an average power conversion efficiency more than 17%. The time resolved photoluminescence showed that the treated samples have obvious effect on the charge carrier dynamics. The striking observation of this study was very low appearance of hysteresis and high reproducibility in the treated samples, which opens up the possibilities for the fabrication of high efficient devices at relatively low temperatures with negligible hysteresis via facile surface modifications.