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Achieving Near-Unity Photoluminescence Efficiency for Blue-violet Emitting Perovskite Nanocrystals
摘要： While the perovskite nanocrystals (NCs) have shown great promise as materials for efficient light emitting diodes (LEDs), low photoluminescence quantum yield (PLQY) of the blue-emitting perovskites is an impediment to the development of white LEDs of which blue is an essential component. Herein, we report that room temperature post-synthetic treatment of weakly blue-violet emitting (PLQY 3%) CsPbCl3 NCs with CdCl2 results in an instantaneous enhancement of the PLQY to near-unity without affecting the PL peak position (406 nm) and spectral width. The time-resolved PL and ultrafast transient absorption measurements confirm the removal of nonradiative defect states of the CsPbCl3 NCs in treated sample. The elemental composition and structural data of the treated sample reveal facile doping of Cd2+ into the crystal lattice without affecting the size and shape of the NCs. Extraordinary PLQY, high air- and photo-stability and ease of preparation of this Cd-doped CsPbCl3 make it by far the most attractive blue-emitting perovskite for development of efficient blue and white LEDs.
关键词： photoluminescence quantum yield,blue-emitting perovskites,perovskite nanocrystals,CdCl2 treatment,white LEDs
更新于2025-09-23 15:21:21
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Highly luminescent blue-emitting In <sub/>1a??x</sub> Ga <sub/>x</sub> P@ZnS quantum dots and their applications in QLEDs with inverted structure
摘要： In order to resolve the issues of uncontrollably high reactivity of tris(trimethylsilyl)phosphine, widely used P precursor, and very low solubility of metal halide precursors in non-coordinating solvent with ligands in the synthesis of environmentally benign III-V quantum dots, we created bis(trimethylsilyl)phosphine, HP(TMS)2, new P precursor with controllable reactivity and new metal complex precursors (Indium-trioctylphosphine, In-TOP; Ga-TOP; Zn-TOP) soluble in octadecene, non-coordinating solvent with dodecanethiol, C12SH. Another challenging issue with III-V quantum dots is to generate highly luminescent photostable blue-emitting nanaocrystals. We present the way of synthesizing pure III-V In1-xGaxP blue-emitting alloy core in non-coordination solvent. Gallium is introduced in the core to adjust the exciton energy effectively and to lessen lattice mismatch with zinc sulfide shell which contributes to the removal of surface defects and the enhancement of the photostability, and thus enhancing the photoluminescent quantum yield (PLQY) and the high color purity of quantum dots with narrow full width at half maximum (FWHM). The blue-emitting quantum dots, In1-xGaxP@ZnS of outstanding quality (PLQY = 65 %, FWHM = 46 nm) is successfully synthesized with our new P and metal complex precursors. Furthermore, we apply those QDs to fabricate blue-emitting quantum dot light-emitting devices (QLEDs) with the external quantum efficiency of 0.20 % which is the best among the III-V-based blue-emitting QLEDs reported so far.
关键词： III-V semiconductors,Photoluminescence,Blue-emitting,QLEDs,Quantum dots
更新于2025-09-23 15:19:57
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Blue-emitting and self-assembled thinner perovskite CsPbBr <sub/>3</sub> nanoplates: Synthesis and formation mechanism
摘要： Low dimensional semiconductor nanomaterials have a great promise for a variety of applications due to their size-dependent and excellent optoelectronic properties. In this work, we developed a strategy to synthesize uniform and very thin CsPbBr3 perovskite nanoplates (NPls) by introducing additional metal bromides. The CsPbBr3 NPls, self-assembled to a face-to-face stacked state, had a thickness of 4.4 nm (equal to only 2 monolayers, 2 MLs) and showed a maximum emission at 437 nm and a narrow FWHM of 14 nm. The formation mechanism of the CsPbBr3 NPls by adding FeBr3 was ascribed to the constrained growth of CsPbBr3 nanocubes when the surface of Cs+ ions was substituted by the protonated oleylammonium from the byproduct OLA-HBr.
关键词： blue-emitting,quantum confinement,self-assembly,CsPbBr3,perovskite nanoplates
更新于2025-09-23 15:19:57
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Facile generation of thermally activated delayed fluorescence and fabrication of highly efficient non‐doped OLEDs based on triazine derivatives
摘要： A series of donor-acceptor-donor triazine-based molecules with thermally activated delayed fluorescence (TADF) properties were synthesized to obtain highly efficient blue-emitting OLEDs with non-doped emitting layer (EML). The targeted molecules use a triazine core as the electron acceptor, and a benzene ring as the conjugated linker with different electron donors to alternate the energy level of HOMO to further tune the emission color. The introduction of long alkyl chains on the triazine core inhibits the unwanted intermolecular D-D/A-A type π-π interactions, resulting in the intermolecular D-A charge transfer. The weak aggregation-caused quenching (ACQ) effect caused by the suppressed intermolecular D-D/A-A type π-π interaction further enhances the emission. The crowded molecular structure allows the electron donor and acceptor to be nearly orthogonal, thereby reducing the energy gap between triplet and singlet excited states (ΔEST). As a result, blue-emitting devices with TH-2DMAC and TH-2DPAC non-doped EML showed satisfactory efficiencies of 12.8% and 15.8%, respectively, which is one of the highest EQEs reported in the blue TADF emitters (λpeak < 475 nm), demonstrating that our tailored molecular designs are promising strategies to endow OLEDs with excellent EL performances.
关键词： triazine derivatives,non-doped emitting layer,OLEDs,blue-emitting,thermally activated delayed fluorescence,TADF
更新于2025-09-19 17:13:59
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Ultrasonication-Assisted Ambient-Air Synthesis of Monodispersed Blue-Emitting CsPbBr3 Quantum Dots for White Light Emission
摘要： Colloidal all-inorganic perovskite CsPbBr3 nanocrystals present versatile outstanding optoelectronic properties, as well as greatly improved stability when compared with their hybrid analogues. However, the performance of blue-emitting CsPbBr3 nanocrystals is still inferior to their green counterpart. Moreover, their synthesis generally demands high temperature and inert gas environment. Synthesis of perovskite nanocrystals with high efficiency blue emission in air ambience is highly desired. In this work we demonstrate a top-down strategy for the facile synthesis of blue-emitting CsPbBr3 quantum dots (QDs) in air ambience, through cutting CsPbBr3 nanoplatelets (NPLs) into spherical QDs with the assistance of ultrasonication and hydrobromic acid (HBr) treatment. The CsPbBr3 QDs show excellent monodispersion with an average size of about 5 nm and a blue emission at 460 nm with high photoluminescence quantum yield (PL QY) of 53.2%. The key role of HBr is suggested to solubilize the inorganic cores of the NPLs and repair the surface. The CsPbBr3 QDs are used to prepare mixed phosphors emitting high quality white light.
关键词： Blue-emitting,Luminescence,Lead halide perovskite,Reprecipitation,Quantum dots,Ambient-Air synthesis
更新于2025-09-19 17:13:59
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A Cocktail of Multiple Cations in Inorganic Halide Perovskite towards Efficient and Highly Stable Blue Light-Emitting Diodes
摘要： Blue-emitting materials and their light-emitting diodes (LEDs) are always challenging in the application of lighting and display. Recently, perovskite LEDs (PeLEDs) with efficient and stable green/red emission have made great progress, where external quantum efficiency (EQE) over 20% has been reached. However, it is still a big challenge to realize stable blue PeLEDs with high efficiency mainly due to the poor film quality and unreasonable device structure. Herein, a cocktail strategy, that is, multi-cation (Cs/Rb/FA/PEA/K)Pb(Cl/Br)3 is demonstrated to improve both the efficiency and stability of blue PeLEDs. Combined with the “insulator-perovskite-insulator” structure, PeLEDs based on multi-cation (Cs/Rb/FA/PEA/K)Pb(Cl/Br)3 perovskite film show maximum EQE of 2.01% and maximum luminance of 4015 cd/m2 at 484 nm. More importantly, the device exhibits robust durability, and its half-lifetime is over 300 min under continuous operation. The multi-cation strategy could open up new avenue to design new blue-emitting materials for high-performing PeLEDs.
关键词： Stability,Multi-cation strategy,Perovskite LEDs,Blue-emitting materials,Efficiency
更新于2025-09-19 17:13:59
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Vacuum-Deposited Blue Inorganic Perovskite Light-Emitting Diodes
摘要： Perovskite light-emitting diodes (PeLEDs) have drawn great research attention due to their outstanding electroluminescence performance by solution processing. PeLEDs made by thermal evaporation are relatively rarely explored but compatible to existing OLED industrial lines. Blue-emitting PeLEDs are all based on organic-containing perovskites, rather than more stable all-inorganic perovskites because of their poor solubility, too fast crystallization, uneven discrete film and unattainable pure blue emission. Here we report all-inorganic, vacuum processed blue PeLEDs. High-throughput combinatorial approaches are employed to optimize Cs:Pb:Br:Cl composition in our dual-source co-evaporation system to achieve the balance between film photoluminescence and injection efficiency. As-deposited perovskite films demonstrated excellent intrinsic stability against heat, UV-light and humidity attack. A series of PeLEDs were obtained covering standard blue spectral region with a best luminance of 121 cd/m2 as well as an EQE of 0.38%. We believe the vacuum processing strategy demonstrated here provide a very promising alternative way to produce efficient and stable all-inorganic blue-emitting PeLEDs.
关键词： all-inorganic perovskite,stability,high-throughput combinatorial approaches,vacuum-deposited,blue-emitting
更新于2025-09-16 10:30:52
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Pyrenylpyridines: Sky-Blue Emitters for Organic Light-Emitting Diodes
摘要： A novel sky-blue-emitting tripyrenylpyridine derivative, 2,4,6-tri(1-pyrenyl)-pyridine (2,4,6-TPP), has been synthesized using a Suzuki coupling reaction and compared with three previously reported isomeric dipyrenylpyridine (DPP) analogues (2,4-di(1-pyrenyl)pyridine (2,4-DPP), 2,6-di(1-pyrenyl)pyridine (2,6-DPP), and 3,5-di(1-pyrenyl)-pyridine (3,5-DPP)). As revealed by single-crystal X-ray analysis and computational simulations, all compounds possess highly twisted conformations in the solid state with interpyrene torsional angles of 42.3°?57.2°. These solid-state conformations and packing variations of pyrenylpyridines could be correlated to observed variations in physical characteristics such as photo/thermal stability and spectral properties, but showed only marginal influence on electrochemical properties. The novel derivative, 2,4,6-TPP, exhibited the lowest degree of crystallinity as revealed by powder X-ray diffraction analysis and formed amorphous thin films as verified using grazing-incidence wide-angle X-ray scattering. This compound also showed high thermal/photo stability relative to its disubstituted analogues (DPPs). Thus, a nondoped organic light-emitting diode (OLED) prototype was fabricated using 2,4,6-TPP as the emissive layer, which displayed a sky-blue electroluminescence with Commission Internationale de L’Eclairage (CIE) coordinates of (0.18, 0.34). This OLED prototype achieved a maximum external quantum efficiency of 6.0 ± 1.2% at 5 V. The relatively high efficiency for this simple-architecture device reflects a good balance of electron and hole transporting ability of 2,4,6-TPP along with efficient exciton formation in this material and indicates its promise as an emitting material for design of blue OLED devices.
关键词： Suzuki coupling reaction,tripyrenylpyridine derivative,OLED,electroluminescence,dipyrenylpyridine,sky-blue-emitting
更新于2025-09-16 10:30:52
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Synthesis of Colloidal Blue-Emitting InP/ZnS Core/Shell Quantum Dots with the Assistance of Copper Cations
摘要： Colloidal InP quantum dots (QDs) have been considered as one of the most promising candidates for the applications in display and bio-label due to intrinsic toxicity-free and high photoluminescence. On account of the uncontrollable nucleation and growth for the synthesis of InP, it remains a challenge to obtain high-quality blue-emitting InP QDs with uniform size distribution. Herein, we employ a novel synthetic approach for producing blue-emitting InP/ZnS core/shell QDs with the assistance of copper cations. The studies reveal that the copper ions could combine with phosphorus precursor to form hexagonal Cu3-xP nanocrystals, which competed with the nucleation process of InP QDs, resulting in the smaller sized InP QDs with blue photoluminescence emission. After the passivation of InP QDs with ZnS shell, the synthesized InP/ZnS core/shell QDs present bright blue emission (~425 nm) with photoluminescence quantum yield (PLQY) of ~25%, which is the shortest wavelength emission for InP QDs till now. This research provides a new way to synthesize ultra-small semiconductor nanocrystals.
关键词： InP/ZnS core/shell,blue-emitting,Colloidal InP quantum dots,photoluminescence quantum yield,copper cations
更新于2025-09-12 10:27:22
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Influence of the Silver Nanocrystal Shape on the Luminous Efficiency of Blue-Emitting Polymer Light-Emitting Diodes
摘要： Truncated silver nanodecahedrons (TAgNDs) and truncated silver nanoplates (TAgNPs) fabricated via chemical reduction and photochemical methods were added to poly[3,4-ethylenedioxythiophene]:poly[styrenesulfonate] (PEDOT:PSS) as a dopant to promote the luminous efficiency of blue-emitting polymer light-emitting diodes (PLEDs). The differences in shape between TAgNDs and TAgNPs result in better dispersion of TAgNDs in PEDOT:PSS. Therefore, at an optimal doping concentration (the distributed density in the light-emitting region is 6.88 μg cm?2 for TAgNDs and 5.16 μg cm?2 for TAgNPs), the average current efficacy and maximum electroluminescence intensity enhancement factor for TAgNDs-doped PLED were 4.18 cd A?1 and 420% respectively, which are much higher than those for TAgNPs-doped PLED (1.83 cd A?1 and 200%) at a luminescence wavelength of 440 nm.
关键词： truncated silver nanoplates,blue-emitting polymer light-emitting diodes,luminous efficiency,truncated silver nanodecahedrons
更新于2025-09-11 14:15:04