Highly Emissive Blue Quantum Dots with Superior Thermal Stability via In Situ Surface Reconstruction of Mixed CsPbBr₃–Cs₄PbBr₆ Nanocrystals

Abstract

Although metal halide perovskites are candidate high-performance light-emitting diode (LED) materials, blue perovskite LEDs are problematic: mixed-halide materials are susceptible to phase segregation and bromide-based perovskite quantum dots (QDs) have low stability. Herein, a novel strategy for highly efficient, stable cesium lead bromide (CsPbBr 3 ) QDs via in situ surface reconstruction of CsPbBr 3 -Cs 4 PbBr 6 nanocrystals (NCs) is reported. By controlling precursor reactivity, the ratio of CsPbBr 3 to Cs 4 PbBr 6 NCs is successfully modulated. A high photoluminescence quantum yield (PLQY) of >90% at 470 nm is obtained because octahedron CsPbBr 3 QD surface defects are removed by the Cs 4 PbBr 6 NCs. The defect-engineered QDs exhibit high colloidal stability, retaining >90% of their initial PLQY after >120 days of ambient storage. Furthermore, thermal stability is demonstrated by a lack of heat-induced aggregation at 120 °C. Blue LEDs fabricated from CsPbBr 3 QDs with reconstructed surfaces exhibit a maximum external quantum efficiency of 4.65% at 480 nm and excellent spectral stability.

Performance Enhancement of Crystal Silicon Solar Cell by a CsPbBr3–Cs4PbBr6 Perovskite Quantum Dot @ZnO/Ethylene Vinyl Acetate Copolymer Downshifting Composite Film

“…The results were similar to previous studies, in which oleylammonium bromide as Br source was applied. [ 61 ] The main diffraction peaks of CsPbBr 3 and Cs 4 PbBr 6 are located at 15.21° and 30.27°, for which the corresponding crystal lattice planes (110) and (223) were assigned respectively. In Figure 1a, we found the inclusion of THABr in the perovskite precursor solution that evidently impacted composition and crystal orientation of perovskite QDs.…”

“…In Figure 6b, we found some absorption peaks of composite films between 410 and 490 nm wavelength, corresponding to the absorption spectra of perovskite QDs. [ 61 ] More importantly, the transmission of perovskite QD/EVA composite films varies with Zn(C 2 H 5 ) 2 composition. Without Zn(C 2 H 5 ) 2 , the prepared composite film has poor transmission due to severe aggregation of perovskite QDs, as depicted by the cloudy precursor solution shown in Figure 4c.…”

Three-Dimensional Lead Halide Perovskites Embedded in Zero-Dimensional Lead Halide Perovskites: Synthesis, Stability, and Applications

“…Lead halide perovskites are promising candidates for future light emitters in display technologies. Despite recently reported studies on highly improved device efficiency, the operational stability of PeLEDs faces challenges. ,, Many approaches, such as surface ligand control, defect passivation, and post-treatment processes, have been studied to improve the operational stability of PeLEDs. − One strategy to improve the efficiency and stability of PeLED is to use 3D-0D halide perovskites. − ,, …”

“…Over the past several years, optoelectronic devices using perovskites have been applied in various fields. In particular, light-emitting diodes and solar cells fabricated using perovskites have attracted considerable attention owing to their excellent optical properties. , However, the intrinsic weak stability of perovskite materials limits their use in electric-charge-based applications. ,− A method of utilizing 0D perovskite has been proposed to address the instability issue of 3D perovskites and facilitate device operation. − The unique isolated structure of 0D perovskites suppresses ion migration and improves performance in terms of device operation time upon the application of an electric field . However, the synthesis should be properly controlled because the structure inhibits the transport of electrons and holes .…”

Highly stable and water dispersible polymer-coated CsPbBr3 nanocrystals for Cu-ion detection in water

“…[39][40][41][42][43][44][45][46][47][48][49] CsPbX 3 @Cs 4 PbX 6 and CsPbBr 3 @Rb 4 PbBr 6 core@shell NCs were also synthesized via a hot-injection method that shows higher luminescence intensity and superior photostability. [50][51][52] The polymers are usually flexible and increase the hydrophobicity of NCs, which improves the water stability. Polyvinyl-pyrrolidone (PVP) polymer encapsulated CsPbBr 3 NCs embedded in a polystyrene (PS) matrix exhibited better water resistance and were demonstrated as luminescent probes in live cells.…”