Stabilizing RbPbBr₃ Perovskite Nanocrystals through Cs⁺ Substitution

Abstract

ABX3‐type halide perovskite nanocrystals (NCs) have been a hot topic recently due to their fascinating optoelectronic properties. It has been demonstrated that A‐site ions have an impact on their photophysical and chemical properties, such as the optical band gap and chemical stability. The pursuit of halide perovskite materials with diverse A‐site species would deepen the understanding of the structure–property relationship of the perovskite family. In this work we have attempted to synthesize rubidium‐based perovskite NCs. We have discovered that the partial substitution of Rb+ by Cs+ help to stabilize the orthorhombic RbPbBr3 NCs at low temperature, which otherwise can only be obtained at high temperature. The inclusion of Cs+ into the RbPbBr3 lattice results in highly photoluminescent Rb1−xCsxPbBr3 NCs. With increasing amounts of Cs+, the band gaps of the Rb1−xCsxPbBr3 NCs decrease, leading to a redshift of the photoluminescence peak. Also, the Rb1−xCsxPbBr3 NCs (x=0.4) show good stability under ambient conditions. This work demonstrates the high structural flexibility and tunability of halide perovskite materials through an A‐site cation substitution strategy and sheds light on the optimization of perovskite materials for application in high‐performance optoelectronic devices.

An All‐Inorganic Perovskite‐Phase Rubidium Lead Bromide Nanolaser

“…The X‐ray diffraction patterns of RbPbBr 3 in Figure c confirm the phase transition from non‐perovskite to perovskite at 290 °C, which agrees well with theoretical simulations. According to the XRD results in Figures c, Figures c and d, the non‐perovskite phase dominates in the directly obtained samples; the main phase of the annealed samples was transformed to a perovskite structure . Figure d depicts the PL and absorption spectra of perovskite‐phase RbPbBr 3 .…”

“…The tolerance factor of RbPbBr 3 is about 0.78 (the effective ionic radii of Rb + , Pb 2+ , and Br − are 1.61, 1.19, and 1.96 Å, respectively). This indicates that RbPbBr 3 perovskite structures are hard to realize and have poor stability . The incorporation of Cs + into RbPbBr 3 will lead to a larger tolerance factor and stabilize the perovskite phase.…”

“…Woodward and Chen et al. thus obtained Rb x Cs 1− x PbBr 3 perovskite quantum dots . So far, the realization of the all‐inorganic perovskite RbPbBr 3 is still a great challenge.…”

“…Up to now, Rb/Cs mixed perovskites have been reported to show better photovoltaic performance . Rb x Cs 1− x PbBr 3 perovskite quantum dots were found to exhibit high quantum yield (93 %), narrower photoluminescence (PL) emission linewidth (18–27 nm), and excellent wide color gamut coverage . However, all‐inorganic perovskite RbPbBr 3 structures have still not been realized.…”

Spectrally Tunable and Stable Electroluminescence Enabled by Rubidium Doping of CsPbBr3 Nanocrystals

“…Finite Rb + incorporation results in further tilting of the PbX 6 octahedra, reducing the overall orbital overlap and hence opening up the bandgap of CsPbBr 3 while simultaneously reducing the tolerance factor . However, it has been reported that an upper bound of 70% Rb + exists in a mixed cation perovskite QD, as pure RbPbBr 3 does not exist under ambient conditions …”