Open AccessHighly Emissive Blue Quantum Dots with Superior Thermal Stability via In Situ Surface Reconstruction of Mixed CsPbBr 3 –Cs 4 PbBr 6 Nanocrystals
Author(s) -
Kim Hyeonjung,
Park Jong Hyun,
Kim Kangyong,
Lee Dongryeol,
Song Myoung Hoon,
Park Jongnam
Publication year - 2022
Publication title -
advanced science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.388
H-Index - 100
ISSN - 2198-3844
DOI - 10.1002/advs.202104660
Subject(s) - perovskite (structure) , quantum dot , photoluminescence , nanocrystal , halide , materials science , light emitting diode , thermal stability , quantum yield , luminescence , optoelectronics , octahedron , diode , colloid , nanotechnology , chemical engineering , chemistry , inorganic chemistry , optics , crystallography , crystal structure , physics , engineering , fluorescence
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.