Investigation of the Role of the Environment on the Photoluminescence and the Exciton Relaxation of CsPbBr₃ Nanocrystals Thin Films

• Main Authors: Marco Anni, Arianna Cretì, Yuhai Zhang, Maria Luisa De Giorgi, Mauro Lomascolo
• Format: Article
• Language: English
• Published: MDPI AG 2020-03-01
• Series: Applied Sciences
• Subjects: lead halide perovskites; nanocrystals; photoluminescence; time resolved photoluminescence; gas sensors
• Online Access: https://www.mdpi.com/2076-3417/10/6/2148

In this work, we present a detailed optical investigation of the effects of the environment on the photoluminescence (PL) spectra and the relaxation dynamics of pristine and aged CsPbBr₃ nanocrystal (NC) thin films. We demonstrate that, contrary to previous results on similar NCs, the PL intensity of pristine NCs is higher when the sample is in wet air than in vacuum, due to the passivation of defects reducing the free exciton trapping and the bound excitons non-radiative relaxation. The aged NCs show a PL intensity increase in wet air nine times stronger than the pristine ones, due to an interplay between static and dynamic effects, increasing the number of emitting NCs and reducing the non-radiative recombination rate of free excitons. These results improve the understanding of the possible interactions between perovskite NCs and the environment, which could be relevant for the development of optical gas sensors exploiting perovskite NCs.