Abstract
All-inorganic perovskite quantum dots (QDs) (CsPbX3, X = Cl, Br, I) become promising candidate materials for the new generation of light-emitting diodes for their narrow emission spectrum, high photoluminescence quantum yield, and adjustable emission wavelength. However, the perovskite QDs materials still face instability against moisture, high-temperature, and UV-light. Many strategies have been reported to improve the photoluminescence (PL) performance of QDs while increasing their stability. These strategies can be divided into three main categories: doping engineering, surface ligand modification, coating strategies. This paper reviews the recent research progress of surface ligands, inorganic and polymer coating, and metal ions doping of CsPbX3 QDs. Partial substitution of Pb2+ with non-toxic or low-toxic metal ions can improve the formation energy of the perovskite lattice and reduce its toxicity. The surface polymer modification can use their ligands to bond with the uncoordinated lead and halogen ions on perovskite QDs surface to reduce surface defects, thereby improving the PL intensity and stability. In addition, the organic or inorganic coating materials on perovskite QDs can effectively avoid their contact with the external environment, thereby improving the stability of the perovskite. The optical properties of the modified QDs, including transient absorption spectra, temperature-dependent PL spectra, time-resolved photoluminescence (TRPL) spectra properties, etc. were discussed to explain the physical mechanism. The potential applications of all-inorganic perovskite QDs as down-conversion fluorescent materials in light-emitting diodes are presented. Finally, we provide some possible methods to further improve the PL performance of the all-inorganic perovskite QDs.
Highlights
All-inorganic perovskite materials have attracted much attention for their high carrier mobility, high radiation recombination efficiency, high color purity, and tunable bandgap, which are considered promising materials for next-generation light-emitting devices (LED) (Akkerman et al, 2018; Fu et al, 2019; Xu et al, 2020a).The perovskite materials have the formula of ABX3, where A generally represents a monovalent organic or metal cation, B often represents a divalent metal cation, and X is a halide anion
Power conversion efficiency of the perovskite solar cell has increased to 25.2% in the last years (Kojima et al, 2009; Roy et al, 2020)
This review focuses on the stability and fluorescence enhancement strategies of all-inorganic CsPbX3 quantum dots (QDs), primarily describing the aspects of doping engineering, surface ligand modification, and surface coating strategies
Summary
All-inorganic perovskite materials have attracted much attention for their high carrier mobility, high radiation recombination efficiency, high color purity, and tunable bandgap, which are considered promising materials for next-generation light-emitting devices (LED) (Akkerman et al, 2018; Fu et al, 2019; Xu et al, 2020a). Fang et al (2021) achieved a high-performance perovskite green QLED through modulating the charge injection balance with the incorporation of a bilayered electron transport structure, while improving efficiency and operating life, a champion external quantum efficiency (EQE) of 21.63%, representing one of the most efficient perovskite QLEDs so far All these reports indicate that the all-inorganic perovskite semiconducting material is ideal for optoelectronic device application. The surface coating method mainly uses transparent wide-bandgap materials to encapsulate and protect the perovskite QDs from the external environment (Liu et al, 2018; Pan et al, 2018; Yajing Chang et al, 2018; Zhang et al, 2018), which dramatically reduces the degradation of QDs, thereby effectively improving their water and oxygen resistances It avoids the reduction of quantum efficiency caused by aggregation and ion exchange effects. We summarize the recent research advances and make an outlook about the future development of the perovskite materials
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