Abstract
All-inorganic CsPbX3 (X = Cl, Br, and I) perovskite quantum dots (PeQDs) have shown great promise in optoelectronics and photovoltaics owing to their outstanding linear optical properties; however, nonlinear upconversion is limited by the small cross-section of multiphoton absorption, necessitating high power density excitation. Herein, we report a convenient and versatile strategy to fine tuning the upconversion luminescence in CsPbX3 PeQDs through sensitization by lanthanide-doped nanoparticles. Full-color emission with wavelengths beyond the availability of lanthanides is achieved through tailoring of the PeQDs bandgap, in parallel with the inherent high conversion efficiency of energy transfer upconversion under low power density excitation. Importantly, the luminescent lifetimes of the excitons can be enormously lengthened from the intrinsic nanosecond scale to milliseconds depending on the lifetimes of lanthanide ions. These findings provide a general approach to stimulate photon upconversion in PeQDs, thereby opening up a new avenue for exploring novel and versatile applications of PeQDs.
Highlights
All-inorganic CsPbX3 (X = Cl, Br, and I) perovskite quantum dots (PeQDs) have shown great promise in optoelectronics and photovoltaics owing to their outstanding linear optical properties; nonlinear upconversion is limited by the small cross-section of multiphoton absorption, necessitating high power density excitation
Previous endeavors on this aspect through non-radiative Förster resonance energy transfer (FRET) from lanthanide-doped NPs to quantum dots usually resulted in serious quenching of overall upconversion luminescence (UCL) intensity and negligibly weak quantum dots emissions, because it is notoriously difficult to control the number of energy acceptors in close proximity of the donors within an effective FRET distance[38,39,40]
High-quality CsPbX3 PeQDs were synthesized through a facile and novel method by injecting HX (X = Cl, Br, and I) to the precursor solution of Cs-oleate and Pb(II)-oleate at an elevated temperature (Methods)
Summary
The luminescent lifetimes of the excitons can be enormously lengthened from the intrinsic nanosecond scale to milliseconds depending on the lifetimes of lanthanide ions These findings provide a general approach to stimulate photon upconversion in PeQDs, thereby opening up a new avenue for exploring novel and versatile applications of PeQDs. All-inorganic cesium lead halide (CsPbX3, X = Cl, Br, and I) perovskite quantum dots (PeQDs) have recently attracted intensive attention in a wide array of research fields, owing to their outstanding physicochemical properties such as large absorption coefficients, high photoluminescence (PL) quantum yields (QYs), narrow emission bands, and tunable bandgap and PL emissions by varying the halide composition[1,2,3,4]. Tunable upconversion emission with wavelengths beyond the availability of lanthanide-doped NPs is likely to be realized via bandgap tailoring of PeQDs, in parallel with the benefits of lifetime tunability by lanthanide ions and the inherent high conversion efficiency of energy transfer upconversion under low power density excitation
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