In Situ Synthesis of UltraStable TiO<sub>2</sub> Coating Rb<sup>+</sup>-Doped Red Emitting CsPbBrI<sub>2</sub> Perovskite Quantum Dots
Yongqiang Ji, Minqiang Wang, Zhi Yang, Hao Wang, Muhammad Amin Padhiar, Jindou Shi, Hengwei Qiu, Arshad Saleem Bhatti
Abstract
Among the lead halide perovskites, the stability of red-emitting CsPbBrI2 perovskite quantum dots (PQDs) is very poor. This is an impediment to the development of high purity white emitting diodes (WLEDs) based on PQDs. Herein, we surprisingly find that luminescent properties of CsPbBrI2 PQDs can be significantly improved through doping of univalent Rb+ ions, especially when molar ratio of Rb+/Cs+ = 0.1/0.9. Subsequently, these red emitting Rb0.1Cs0.9PbBrI2 PQDs are successfully coated with TiO2 through an easy in situ strategy of adding titanium(IV) butoxide (TBO) to the precursor. Benefiting from the efficient protection of TiO2 nanoshell, these highly fluorescent Rb0.1Cs0.9PbBrI2/TiO2 nanocomposites can preserve their excellent red emitting characteristics even when directly immersed in water or exposed to illumination, enabling us to build highly stable WLEDs with color coordinates at (0.342, 0.325).