Room-temperature efficient photoluminescence mechanism of indium doping lead-free colloidal MA₃Bi₂Br₉ quantum dots...

Lead halide perovskite quantum dots (QDs) are promising candidates for future optoelectronic devices due to their excellent photonic and electronic properties. However, poor stability and toxicity problems limit their further development. This work demonstrates the doping tactics to boost the optical properties of lead-free colloidal MA₃Bi₂Br₉ QDs, the indium ion (In³⁺) doping presented herein is found to be effective in improving the photoluminescence (PL) properties of MA₃Bi₂Br₉ (CH₃NH₂ = MA) QDs without alerting their favorable electronic structure. It has been elucidated by microscopy and diffraction results that the In³⁺ doping optimizes the QDs solution octahedron structure, and the PL red-shifted phenomenon coincides well with the analogous red-shifted obtained in the ultraviolet/visible (UV-Vis) absorption spectroscopy, which is due to the quantum confinement effect. And the nanosecond transient absorption (ns-TA) spectroscopy elucidates that the enhanced radiative recombination process contributes to enhanced stability and luminescence. The photoluminescence quantum yield (PLQY) of MA₃Bi₂Br₉ QDs is increased by 60.7%. This work offers a valid strategy for improving the quality of the lead-free perovskite QDs.