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Original Article Open Access
Highly efficient emission and high-CRI warm white light-emitting diodes from ligand-modified CsPbBr3 quantum dots
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Abstract
All-inorganic CsPbBr3 perovskite quantum dots (QDs) have received great attention in white light emission because of their outstanding properties. However, their practical application is hindered by poor stability. Herein, we propose a simple strategy to synthesize excellent stability and efficient emission of CsPbBr3 QDs by using 2-hexyldecanoic acid (DA) as a ligand to replace the regular oleic acid (OA) ligand. Thanks to the strong binding energy between DA ligand and QDs, the modified QDs not only show a high photoluminescence quantum yield (PLQY) of 96% but also exhibit high stability against ethanol and water. Thereby warm white light-emitting diodes (WLEDs) are constructed by combining ligand modified CsPbBr3 QDs with red AgInZnS QDs on blue emitting InGaN chips, exhibiting a color rendering index of 93, a power efficiency of 64.8 lm/W, a CIE coordinate of (0.44, 0.42) and correlated color temperature value of 3018 K. In addition, WLEDs based on ligand modified CsPbBr3 QDs also exhibit better thermal performance than that of WLEDs based on the regular CsPbBr3 QDs. The combination of improved efficiency and better thermal stability with high color quality indicates that the modified CsPbBr3 QDs are ideal for WLEDs application.-
Keywords:
- CsPbBr3 quantum dots /
- ligand modification /
- stability /
- efficiency /
- white light-emitting diodes
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References
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Supplementary information for Highly efficient emission and high-CRI warm white light-emitting diodes from ligandmodified CsPbBr3 quantum dots 
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Figure 1.
Relaxed surface models for simulating the adsorption of OA/DA molecules on the CsPbBr3 surface. The insets are the zoomed-in plot of the bonded regions. (a) OA on top of the pristine CsBr-terminated surface. (b) DA on top of the pristine CsBr-terminated surface. (c) OA bonding with a Br-vacancy. (d) DA bonding with a Br-vacancy. (e) The binding energies of the four interfaces.
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Figure 2.
(a) The schematic illustration of the surface in the CsPbBr3 QDs with ligand modification process. (b) Photographs of the CsPbBr3 QDs solution under the daylight (left) and UV light of 365 nm (right). (c) HRTEM images. (d) XRD patterns. (e) FTIR spectra. (f)1H-NMR spectra after washed twice.
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Figure 3.
(a) PL spectra. (b) Absorption spectra. (c) PL decays and (d, e) AFM images of the QDs films.
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Figure 4.
CsPbBr3-OA QDs and CsPbBr3-DA QDs in ethanol. (a) Photographs. (b, c) PL spectra. (d) PL intensity variation of QDs solutions over 90 min.
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Figure 5.
Photographs of CsPbBr3 QDs solution under daylight and UV light of 365 nm.
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Figure 6.
(a) PL spectrum of WLEDs based on CsPbBr3-OA QDs with a CRI of 82. (b) PL spectrum of WLEDs based on CsPbBr3-DA QDs with a CRI of 93 (The inset shows photographs of the devices without and with driving voltage). (c) CIE chromaticity diagram of both WLEDs.
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Figure 7.
The thermal imaging photographs of (a) CsPbBr3-OA QDs WLEDs and (b) CsPbBr3-DA QDs WLEDs with various driving current.
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