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Quantum size effect and surface defect passivation in size-controlled CsPbBr3 quantum dots
摘要： Luminescent CsPbBr3 quantum dots (QDs) with adjustable size and bandgap were grown by controlling the synthesis temperature in this paper. As the synthesis temperature increases, the QD size becomes larger and then smaller. The corresponding absorption and steady-state photoluminescence spectrum indicate that the QD band gap becomes smaller and then larger, which is a typical quantum confinement effect. Time-resolved photoluminescence spectrum and femtosecond transient absorption spectrum (fs-TAS) show that the non-radiative recombination probability of photocarriers in small QDs is small it has few defects, indicating that the ligand molecules adsorbed on the surface of QDs effectively passivate the surface defects of CsPbBr3. Finally, the hot-phonon bottleneck effect of CsPbBr3 QDs is revealed by the kinetic curves fitting of fs-TAS and the cooling kinetic process of hot carriers is also discussed in detail. This work provides new insights on size-dependent photophysical properties of CsPbBr3 QDs.
关键词： Quantum confinement effect,Metal halide perovskite QDs,Defect passivation,Hot carriers
更新于2025-09-23 15:19:57
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High staility of silica-wrapped CsPbBr3 perovskite quantum dots for light emitting application
摘要： Encapsulating quantum dots (QDs) into other medium has been considered as an efficacious method to avoid the fluorescence degradation of QDs. Here, we proposed a facile method to embed CsPbBr3 perovskite QDs in silica matrix derived from (3-aminopropyl)triethoxysilane (APTES) at room temperature in open air. The QDs/SiO2 composite was extracted from the sol-gel solution by using a precipitation-encapsulation method assisted with APTES. As-prepared composite powder possess a high photoluminescence quantum yield (PLQY) of 68% and a full width at half maximum (FWHM) of ~23 nm. The QDs/SiO2 compounds show excellent stability after the five heating cycles (105 °C) and a continuous xenon irradiation (500 W, 70 °C). Besides, the products remain 94.3% and 98.6% photoluminescence (PL) intensity after 30 days of storage (25 °C) and 96 hours of ultraviolet (UV) irradiation (λ= 365 nm) respectively. The white light-emitting diode (LED) was fabricated by coating green-emitting CsPbBr3@SiO2 composite powder and commercial red phosphors on blue chip. The fabricated white LED performed excellent light characteristics with a luminous efficacy (ηL) of 58.9 lmW-1 and a correlated color temperature (CCT, Tc) of 5829 K (current = 20 mA), it also display a wide color gamut with 126.8% of National Television System Committee (NTSC) color triangle area.
关键词： white LED,stability,perovskite QDs,CsPbBr3,SiO2
更新于2025-09-19 17:13:59
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Confinement of Perovskite‐QDs within a Single MOF Crystal for Significantly Enhanced Multiphoton Excited Luminescence
摘要： The development of the photostable higher-order multiphoton-excited (MPE) upconversion single microcrystalline material is fundamentally and technologically important, but very challenging. Here, up to five-photon excited luminescence in a host–guest metal–organic framework (MOF) and perovskite quantum dot (QD) hybrid single crystal ZJU-28?MAPbBr3 is shown via an in situ growth approach. Such a MOF strategy not only results in a high QD loading concentration, but also significantly diminishes the aggregation-caused quenching (ACQ) effect, provides effective surface passivation, and greatly reduces the contact of the QDs with the external bad atmosphere due to the confinement effect and protection of the framework. These advantages make the resulting ZJU-28?MAPbBr3 single crystals possess high PLQY of ≈51.1%, a high multiphoton action cross-sections that can rival the current highest record (measured in toluene solution), and excellent photostability. These findings liberate the excellent luminescence and nonlinear optical properties of perovskite QDs from the solution system to the solid single-crystal system, which provide a new avenue for the exploitation of high-performance multiphoton excited hybrid single microcrystal for future optoelectronic and micro–nano photonic integration applications.
关键词： single crystals,multiphoton excited luminescence,metal–organic frameworks,perovskite-QDs
更新于2025-09-04 15:30:14