Abstract
Despite intensive efforts, the fluorescence of perovskite nanocrystals (NCs) still suffers from a poor color purity, which limits the applications in light emitting and multicolor display. A deep understanding on the fundamental of the photoluminescent (PL) spectral broadening is thus of great significance. Herein, the PL decay curves of the CsPbClxBr3-x NCs are monitored at different wavelengths covering the entire PL band. Moreover, energy relaxation time τ and radiative recombination time β are obtained by numerical fittings. The dependences of τ and 1/β on the detection wavelength agree well with the steady-state PL spectrum, indicating the observed PL broadening is an intrinsic effect due to the resonance and off-resonance exciton radiative recombination processes. This work not only provides a new analysis method for time-resolved PL spectra of perovskites, but also gains a deep insight into the spectral broadening of the lead halide perovskite NCs.
Highlights
The lead halide perovskites nanocrystals (NCs) have attracted extensive interest due to their potential applications for low-cost and high-efficiency photovoltaic, light-emitting diodes (LEDs), and photo-detectors [1,2,3,4,5,6,7,8,9,10,11,12,13]
NCs in this work is better than general preparation [30], while it is inferior to perovskite NCs with precise control, [19] representing a general situation
In order to ensure the broad applicability of the conclusion and to include the possible contribution from size inhomogeneity, the synthesis in this work has not been optimized to eliminate the size in-homogeneity
Summary
The lead halide perovskites nanocrystals (NCs) have attracted extensive interest due to their potential applications for low-cost and high-efficiency photovoltaic, light-emitting diodes (LEDs), and photo-detectors [1,2,3,4,5,6,7,8,9,10,11,12,13]. The limited emission color purity due to the broad spectral width, have hindered the further development of high-performance perovskite LEDs [17,18,19]. Current efforts are focused on exploring of colloidal solutions of perovskite NCs with narrow size distributions to address this issue. Despite intensive efforts, these perovskite NCs are still suffering from a broad bandwidth. The ion migration induced phase segregation may lead to spectral broadening of mixed halide perovskite NCs [26,27,28,29]. The results indicate that the PL broadening is an intrinsic effect due to the resonance and off-resonance exciton radiative recombination processes
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