Photoluminescence quenching of inorganic cesium lead halides perovskite quantum dots (CsPbX3) by electron/hole acceptor

Recently, all-inorganic cesium lead halide perovskites (CsPbX3) quantum dots (QDs) have attracted great attention due to their halogen composition and size tunable band gap engineering, the same physical mechanism that is responsible for excellent performance in light-emitting devices. However, little is known about the time-resolved fluorescence quenching dynamics process of these CsPbX3 QDs. In this article, we present comprehensive contrastive spectral studies on the electron and hole extraction dynamics of CsPbX3 colloidal QDs with and without quencher by time-resolved femtosecond transient absorption (TA) and time-correlated single-photon counting (TCSPC) spectroscopy methods. We have identified that the partial electrons of the conduction band and holes of the valence band of CsPbX3 QDs can be directly extracted by tetracyanoethylene (TCNE) and phenothiazine (PTZ), respectively. Moreover, compared with the CsPbBr3 QDs, the CsPbI3 QDs showed relatively slower charge extraction rates. We also found that the CsPbBr3 QDs with smaller size showed faster carrier recombination rates and photoluminescence (PL) decay lifetime due to the relatively stronger quantum confinement effects. We believe that this study may be useful for realising optimal applications in photovoltaic and light emission devices.