Open AccessElectroluminescent Warm White Light‐Emitting Diodes Based on Passivation Enabled Bright Red Bandgap Emission Carbon Quantum Dots
Author(s) -
Jia Haoran,
Wang Zhibin,
Yuan Ting,
Yuan Fanglong,
Li Xiaohong,
Li Yunchao,
Tan Zhan'ao,
Fan Louzhen,
Yang Shihe
Publication year - 2019
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.201900397
Subject(s) - electroluminescence , passivation , photoluminescence , band gap , optoelectronics , materials science , excited state , quantum yield , diode , light emitting diode , quantum efficiency , conjugated system , chemistry , photochemistry , fluorescence , nanotechnology , optics , physics , polymer , atomic physics , layer (electronics) , composite material
The development of efficient red bandgap emission carbon quantum dots (CQDs) for realizing high‐performance electroluminescent warm white light‐emitting diodes (warm‐WLEDs) represents a grand challenge. Here, the synthesis of three red‐emissive electron‐donating group passivated CQDs (R‐EGP‐CQDs): R‐EGP‐CQDs‐NMe 2 , ‐NEt 2 , and ‐NPr 2 is reported. The R‐EGP‐CQDs, well soluble in common organic solvents, display bright red bandgap emission at 637, 642, and 645 nm, respectively, reaching the highest photoluminescence quantum yield (QY) up to 86.0% in ethanol. Theoretical investigations reveal that the red bandgap emission originates from the rigid π‐conjugated skeleton structure, and the ‐NMe 2 , ‐NEt 2 , and ‐NPr 2 passivation plays a key role in inducing charge transfer excited state in the π‐conjugated structure to afford the high QY. Solution‐processed electroluminescent warm‐WLEDs based on the R‐EGP‐CQDs‐NMe 2 , ‐NEt 2 , and ‐NPr 2 display voltage‐stable warm white spectra with a maximum luminance of 5248–5909 cd m −2 and a current efficiency of 3.65–3.85 cd A −1 . The warm‐WLEDs also show good long‐term operational stability ( L / L 0 > 80% after 50 h operation, L 0 : 1000 cd m −2 ). The electron‐donating group passivation strategy opens a new avenue to realizing efficient red bandgap emission CQDs and developing high‐performance electroluminescent warm‐WLEDs.