Unveiling the Photo‐ and Thermal‐Stability of Cesium Lead Halide Perovskite Nanocrystals
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Lead halide perovskites possess unique characteristics well‐suited for optoelectronic and energy capture devices, however, concerns about their long‐term stability remain. All‐inorganic CsPbX3 (X = Cl, Br, I) perovskite nanocrystals have been reported with improved stability. We investigate the photo‐ and thermal‐stability properties of CsPbX3 (X = Cl, Br, I) nanocrystals by electron microscopy, x‐ray diffraction, thermogravimetric analysis, ensemble and single particle spectral characterization. CsPbBr¬3 is stable under 1‐sun illumination for 16 h in ambient conditions, although single crystal analysis indicates the luminescence states change over time. CsPbBr¬3 is also stable to heating to 250 °C. Large CsPbI3 crystals (34 ± 5 nm) are the least stable under the same conditions; and with heating, the γ (black) phase reverts to the non‐luminescent δ phase. Smaller CsPbI3 nanocrystals (14 ± 2 nm) purified by a different washing strategy exhibit improved photostability with no evidence of crystal growth but are still thermally unstable. Both CsPbCl3 and CsPbBr3 show crystal growth under irradiation or heat, likely with a preferential orientation. TGA‐FTIR reveals nanocrystal mass loss was only from liberation and subsequent degradation of surface ligands. Encapsulation or other protective strategies should be employed for long‐term stability under conditions of high irradiance or temperature.
This is the peer-reviewed version of the following article: Boote, Brett W., Himashi P. Andaraarachchi, Bryan A. Rosales, Rafael Blome-Fernández, Feng Zhu, Malinda D. Reichert, Kalyan Santra, Jingzhe Li, Jacob W. Petrich, Javier Vela, and Emily A. Smith. "Unveiling the Photo‐and Thermal‐Stability of Cesium Lead Halide Perovskite Nanocrystals." ChemPhysChem. (2019), which has been published in final form at https://doi.org/10.1002/cphc.201900432. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Posted with permission.