Abstract
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‐NMe2, ‐NEt2, and ‐NPr2 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 ‐NMe2, ‐NEt2, and ‐NPr2 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‐NMe2, ‐NEt2, and ‐NPr2 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.
Highlights
(CQDs) for realizing high-performance electroluminescent warm white light sources,[4,5] are susceptible to energy light-emitting diodes represents a grand challenge
The crucial issue involved with achieving warm white EL is the rational design of active-emitting layer (EML), where a red electroluminescent material (REM) is undoubtedly essential in complementing avenue to realizing efficient red bandgap emission Carbon quantum dots (CQDs) and developing the red light component and lowering the high-performance electroluminescent warm-White light-emitting diodes (WLEDs)
Synthesis of R-EGP-CQDs-NMe2, -NEt2, and -NPr2 were carried out based on the reported method,[24] involving the solvothermal treatment of N,N-dimethyl, N,N-diethyl, and N,N-dipropyl-pPD as precursors in dimethyl formamide (DMF) (5 mg mL−1) at 200 °C for 12 h, respectively (Figure 1a)
Summary
(CQDs) for realizing high-performance electroluminescent warm white light sources,[4,5] are susceptible to energy light-emitting diodes (warm-WLEDs) represents a grand challenge. Electroluminescent WLEDs rely on direct charge carrier injection into the light-emitting layer without energy bandgap emission at 637, 642, and 645 nm, respectively, reaching the highest losses, permitting full use of the easy photoluminescence quantum yield (QY) up to 86.0% in ethanol. The crucial issue involved with achieving warm white EL is the rational design of active-emitting layer (EML), where a red electroluminescent material (REM) is undoubtedly essential in complementing avenue to realizing efficient red bandgap emission CQDs and developing the red light component and lowering the high-performance electroluminescent warm-WLEDs. White light-emitting diodes (WLEDs) have become a strong (QY),[13] narrow emission and good organic solubility are contender as the future solid-state lighting sources owing to available for fabricating QDs-based electroluminescent warmtheir advantages of high luminous efficiency, high luminance, WLEDs.[14,15]. It is of paramount importance to develop REM with high QY, favorable organic solubility, broad emission bandwidths, and nontoxicity for electroluminescent warm-WLEDs
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