Photo-stability of CsPbBr3 perovskite quantum dots for optoelectronic application

Due to their superior photoluminescence (PL) quantum yield (QY) and tunable optical band gap, all-inorganic CsPbBr3 perovskite quantum dots (QDs) have attracted intensive attention for the application in solar cells, light emitting diodes (LED), photo detectors and laser devices. In this scenario, the stability of such materials becomes a critical factor. We hereby investigated the long-term stability of as-synthesized CsPbBr3 QDs suspended in toluene at various environmental conditions involving the light illumination, atmosphere, and temperature. We found light illumination would induce dramatic degradation of CsPbBr3 QDs reflecting as decreasing absorbance and PL intensity together with red-shifted emission band. Such light instability can be attributed to the photo-induced surface degradation and aggregation. The steady-state spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) technics verified that CsPbBr3 QDs trend to aggregate to form larger particles under continuous light soaking. In addition, decreasing PL QY of the QDs during light soaking indicates the formation of trap sites. Such trap sites lead to the red-shifted emission with increasing PL lifetime. Our work reveals that the main origin of instability in CsPbBr3 QDs and provide reference to engineer such QDs towards optimal device application.