Ultra‐Stable and Highly Efficient White Light Emitting Diodes through CsPbBr3 Perovskite Nanocrystals−Silica Composite Phosphor Functionalized with Surface Phenyl Molecules. Issue 7 (3rd December 2022)

• Record Type: Journal Article
• Authors: Yoon, Soyeon; Seo, Minjun; Kim, In Soo; Lee, Kwangyeol; Woo, Kyoungja
• Is Part Of: Small. Volume 19:Issue 7(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-12-03
• Subjects: aging -- compact silica -- enhanced photoluminescence -- operational stability -- thermal curing; Nanotechnology -- Periodicals; Nanoparticles -- Periodicals; Microtechnology -- Periodicals; 620.5
• DOI: 10.1002/smll.202206311
• Languages: English
• ISSNs: 1613-6810

Abstract

Abstract: Poor stability of CsPbBr3 perovskite nanocrystals (NCs) to moisture/heat/light has significantly limited their application as a green phosphor, despite their outstanding luminescent properties. Here, a remarkably stable CsPbBr3 NCs−silica composite phosphor functionalized with surface phenyl molecules (CsPbBr3 −SiO2 Ph ) is synthesized by controlling low‐temperature hydrolysis and condensation reaction of perhydropolysilazane in the presence of CsPbBr3 NCs followed by phenyl‐functionalization. Through the process, CsPbBr3 NCs are confined in a compact silica matrix, which is impermeable to H2 O. The synthesis strategy is extended to a classical red quantum dot, CdZnSeS@ZnS NCs, to fabricate a white light emitting diode (WLED) consisting of CsPbBr3 −SiO2 Ph and CdZnSeS@ZnS−SiO2 Ph phosphor and silicone resin packaged on a commercial blue InGaN chip with luminous efficacy (LE) of 9.36 lm W −1 . The WLED undergoes enhancements in both green and red photoluminescence over time to achieve a highly efficient performance of 38.80 lm W −1 . More importantly, the WLED exhibits unprecedented operational stability of LE/LE0 = 94% after 101 h‐operation at 20 mA (2.56 V). The ultra‐high operational stability and efficient performance are mainly attributed to thermal curing and aging through which grain growth occurs as well as deactivation of defect states by permeated atmospheric O2 . Abstract : Highly efficient (38.80 lm W −1 ) white LEDs incorporating CsPbBr3 NCs−SiO2 Ph phosphor exhibit unprecedented operational stability of 94% after continuous operation of 101 h. The high stability and performance originate from grain growth and striking photoluminescence‐enhancement (>3‐fold), respectively, upon thermal curing/aging in air. The low‐temperature synthesis strategy reported herein provides a realistic pathway toward synthesizing perovskite NC‐based phosphors for practical applications.