| 1. |
- Gao, Zhaoju, et al.
(författare)
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Short-chain ligand achieves ultra-stable CsPbX3 perovskite quantum dots for white light-emitting diodes
- 2024
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 124:4
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Tidskriftsartikel (refereegranskat)abstract
- All-inorganic perovskite quantum dots (PeQDs) have aroused great research interest in white light-emitting diodes (WLED) due to their excellent optoelectronic properties, but the poor stability, caused by dynamically binding long-chain capping ligands, hinders their future practical applications. To address this issue, here, we exploit short-chain butyric acid (BA) to replace long-chain oleic acid (OA) as capping ligand of CsPbX3 PeQDs by a hot-injection method. The addition of BA not only makes the morphology of CsPbBr3 PeQDs uniform and improves the crystallinity but also effectively suppresses nonradiative recombination, achieving a near unit photoluminescence quantum yield of 96%. The BA capped CsPbBr3 PeQDs exhibit high stability up to 180 d stored in ambient environment and also significantly improved resistance against polar solvent, ultra-violet lamp irradiation, and heat, which is rationalized by the strong binding capacity and shortened distance of BA to the PeQDs through ab initio calculations. Furthermore, by combining green-emission CsPbBr3 and red-emission CsPbBr0.8I2.2 PeQDs with blue GaN chip, we achieved WLEDs with excellent luminous properties, showing their great potential in practical application of wide-color-gamut display and lighting.
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| 2. |
- Liu, Yong-feng, et al.
(författare)
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A turn-on ratiometric fluorescent nanoprobe based on AgInZnS and nitrogen-doped graphene quantum dots for Cd2+ detection in lake water
- 2022
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Ingår i: Journal of Materials Science. - : Springer Nature. - 0022-2461 .- 1573-4803. ; 57:36, s. 17336-17346
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Tidskriftsartikel (refereegranskat)abstract
- Excessive Cd2+ poses adverse influences on ecosystem and human beings, but its precise detection via a facile and environment-friendly method with resistance to interference is still a challenge. Here, a turn-on ratiometric fluorescent nanoprobe for Cd2+ detection is established using yellow-emission AgInZnS quantum dots (AIZS QDs) and blue-emission nitrogen-doped graphene quantum dots (NGQDs), which serve as a recognition unit and internal reference signal, respectively. Cd2+ could enhance the fluorescence of AIZS QDs due to the passivation of surface defects, while it has no significant effect on that of NGQDs. This nanoprobe has a large detection range from 0.5 to 100 µM and a limit of detection low to 28.6 nM. It shows strong anti-interference ability for Cd2+ even in lake water samples with recovery from 98 to 101% and low relative standard deviation of 1.01%, indicating its excellent effectuation to real-application world.
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| 3. |
- Liu, Yong-feng, et al.
(författare)
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Sulfur quantum dot as a fluorescent nanoprobe for Fe3+ ions : Uncovering of detection mechanism, high sensitivity, and large detection range
- 2023
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Ingår i: Journal of Luminescence. - : Elsevier. - 0022-2313 .- 1872-7883. ; 257
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Tidskriftsartikel (refereegranskat)abstract
- Sulfur quantum dots (SQDs), as a novel metal-free fluorescent material, are getting increasingly tremendous attention in metal ion detection, especially for Fe3+, due to the merits of antimicrobial potential, low toxicity, and exciting optoelectronic properties. However, sensing mechanism of SQD based fluorescent probe for Fe3+ is not clear yet, and high sensitivity and large detection range remain a challenge. Here, we report the synthesis of hydrophilic SQDs as a fluorescent nanoprobe for Fe3+ via a fluorescent turn-off mode. We systematically studied the quenching mechanism by ultraviolet–visible absorption spectra, steady-state and time-resolved photoluminescent spectra, and temperature-dependent quenching constants. Results unclearly evidenced the quenching behavior to both inner filter effect and static quenching. Furthermore, the nanoprobe presents a large detection range from 2.5 to 700 μM and a limit of detection low to 53.6 nM, both of which are the record performance to our knowledge. At last, it shows high selectivity toward Fe3+ and presents no ionic strength effect in the range of investigation, which enables surprising results for Fe3+ detection in deionized water with interference ion and real water samples.
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| 4. |
- Liu, Yong-feng, et al.
(författare)
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The influence of the capping ligands on the optoelectronic performance, morphology, and ion liberation of CsPbBr3 perovskite quantum dots
- 2023
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Ingår i: Nano Reseach. - : Springer Nature. - 1998-0124 .- 1998-0000. ; 16:7, s. 10626-10633
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Tidskriftsartikel (refereegranskat)abstract
- Perovskite quantum dots (PeQDs) endowed with capping ligands exhibit impressive optoelectronic properties and enable for cost-efficient solution processing and exciting application opportunities. We synthesize and characterize three different PeQDs with the same cubic CsPbBr3 core, but which are distinguished by the ligand composition and density. PeQD-1 features a binary didodecyldimethylammonium bromide (DDAB) and octanoic acid capping ligand system, with a high surface density of 1.53 nm−2, whereas PeQD-2 and PeQD-3 are coated by solely DDAB at a gradually lower surface density. We show that PeQD-1 endowed with highest ligand density features the highest dispersibility in toluene of 150 g/L, the highest photoluminescence quantum yield of 95% in dilute solution and 59% in a neat film, and the largest core-to-core spacing in neat thin films. We further establish that ions are released from the core of PeQD-1 when it is exposed to an electric field, although it comprises a dense coating of one capping ligand per four surface core atoms. We finally exploit these combined findings to the development of a light-emitting electrochemical cell (LEC), where the active layer is composed solely of solution-processed pure PeQDs, without additional electrolytes. In this device, the ion release is utilized as an advantage for the electrochemical doping process and efficient emissive operation of the LEC.
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| 5. |
- Zhu, Xiaolin, et al.
(författare)
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Capping ligand engineering enables stable CsPbBr3 perovskite quantum dots toward white-light-emitting diodes
- 2023
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 62:23, s. 9190-9198
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Tidskriftsartikel (refereegranskat)abstract
- All-inorganic perovskite quantum dots (PeQDs) have sparked extensive research focus on white-light-emitting diodes (WLEDs), but stability and photoluminescence efficiency issues are still remain obstacles impeding their practical application. Here, we reported a facile one-step method to synthesize CsPbBr3 PeQDs at room temperature using branched didodecyldimethylammonium fluoride (DDAF) and short-chain-length octanoic acid as capping ligands. The obtained CsPbBr3 PeQDs have a near-unity photoluminescence quantum yield of 97% due to the effective passivation of DDAF. More importantly, they exhibit much improved stability against air, heat, and polar solvents, maintaining >70% of initial PL intensity. Making use of these excellent optoelectronic properties, WLEDs based on CsPbBr3 PeQDs, CsPbBr1.2I1.8 PeQDs, and blue LEDs were fabricated, which show a color gamut of 122.7% of the National Television System Committee standard, a luminous efficacy of 17.1 lm/W, with a color temperature of 5890 K, and CIE coordinates of (0.32, 0.35). These results indicate that the CsPbBr3 PeQDs have great practical potential in wide-color-gamut displays.
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