Effect of CdSe/ZnS quantum dots on temperature-dependent luminescence properties in mixed halide perovskites

초록

The temperature-dependent dynamics of organic cations are known to influence the optical properties of lead halide pemvskites (CH3NH3PbX3) significantly. The Rashba splitting effect and internal electric field induced due to the strong spin-orbit coupling and absence of inversion symmetry in the lead halide pemvskites (PS) lead to a decrease in the radiative recombination rates. This study has investigated the luminescence properties of the mixed halide PS (CH3NH3PbI2Br) covered with CdSe/ZnS quantum dots (QDs) (QD/PS hybrid structure) using temperature-dependent photoluminescence (PL) and time-resolved PL spectroscopy. A shorter radiative lifetime obtained in the QD/PS hybrid structures as compared to the bare PS film was attributed to the screening effects of the Rashba splitting and internal electric field due to the charge carrier transfer from QDs to PS. The PL intensity and the PL decay times of the QD/PS hybrid structures increased when compared to those of the bare PS film because of the surface-passivation and charge transfer (CT) effects. The CT from the QDs to PS leads to an enhancement in the radiative recombination due to the enhanced oscillator strength by the screened internal electric field and Rashba splitting, which is induced by an increase in the charge carriers.

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