Quantum dot color conversion is a key technology to fabricate full-color display panels. Because the optical performance of color conversion films is strongly correlated with the dispersion and concentration of quantum dots in the composite films, high loading quantum dots solution is of great importance. Herein, we fabricate a series of poly(ethylene glycol) (PEG)-ylated quantum dots in neutral solvents such as propylene glycol monomethyl ether acetate (PGMEA) and ethylene glycol dimethacrylate (EGDMA), achieving a maximum concentration of 50 wt% with a maximum photoluminescence quantum yield of ~96%. Using PEGylated QDs in EGDMA, we developed quantum dot photoresist to fabricate color conversion patterns, achieving a high blue-light absorption over 90% at 450 nm with a photo conversion efficiency exceeding 55%. Furthermore, high-resolution color conversion patterns with a pixel density of up to 2450 pixels per inch (PPI) were successfully fabricated via direct photolithography. This work not only provides advanced materials for fabricating color conversion patterns for display application, but also opens up new opportunities for other technology.

In this work, we report alcohol induced surface charging of colloidal quantum dots for controllable electrophoretic deposition processing. By adding a fixed amount of alcohol into a preformed quantum dots solution in non-polar solvents, quantum dots can be positively charged, and then deposited on negative electrode under applied electric field. The surface charging of PbSe quantum dots was investigated by Zeta potential, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and discrete Fourier transform calculations. Based on the results, Zeta potential of oleate acid capped PbSe quantum dots increases from +1.6 to +13.4 mV as the amount of alcohol solvent increases. The alcohol induced Zeta potential increase can be explained by the electron cloud shift of active hydrogen mediated by intermolecular hydrogen bonds between carboxylic acid and alcohol. Considering the influence of surface charging of quantum dots on their dispersibility, we describe the microscopic mechanism of alcohol induced electrophoretic deposition processing. Furthermore, we developed a size-selective separation protocol by controlling alcohol induced electrophoretic deposition processing.

Blue emissive quantum dots are key materials in emerging light-emitting technologies for display applications. Herein, we report the synthesis of ZnSeTe/CdZnSe-based type-II core–shell quantum dots with a low Cd content of less than 2.5%. By modifying the Cd content of the CdZnSe shell, photoluminescence emission can be tuned from 430 to 510 nm with a full width at half maximum of less than 26 nm. Transient absorption spectra illustrate the charge transfer between the conduction band of ZnSeTe and the conduction band of CdZnSe, as well as the recombination between the valence band of ZnSeTe and the conduction band of CdZnSe. By subsequent growth of ZnSe and ZnS shells, the resulting quantum dots achieved a photoluminescence quantum yield of 95%. We further demonstrate a blue quantum dot light-emitting diode with an emission peak at 467 nm, showing a maximum external quantum efficiency of 5%, a maximum luminance of 10,376 cd·m⁻², and an extrapolated T₉₅ lifetime of 4.7 h.

Blue emissive quantum dots are key materials in fabricating quantum-dot light-emitting diodes for display applications. Up to date, most of the previous blue emissive quantum dots are based on quantum dots with type-I core-shell structure. In this work, we report pure-blue emissive ZnSe/Cd_xZn_1−xS/ZnS quantum dots with type-II core-shell structure, which show high photoluminescence quantum yield over 90%. The type-II structure was investigated by applying time-resolved photoluminescence and transient absorption measurements, illustrating the extended photoluminescence decay lifetime of ZnSe/Cd_xZn_1−xS quantum dots as well as the transition of bleaching peak from the valence band of ZnSe to the conduction band of CdZnS. We further fabricated ZnSe/Cd_xZn_1−xS/ZnS quantum dots based electroluminescence devices, achieving a maximum external quantum efficiency of 6.7% and a maximum luminance of 39,766 cd·m⁻².

The potential use of large-size ZnSe quantum dots as blue emitters for display applications has greatly inspired the colloidal synthesis. Herein, we report the negative effects of side reactions of large-size ZnSe quantum dots. The side reactions between oleic acid and oleylamine generated amidation products and H₂O, which led to the hydrolysis of Zn(OA)₂ to Zn(OH)₂ and the subsequent formation of zinc oxide (ZnO) and zinc bis[diphenylphosphinate] (Zn(DPPA)₂) precipitates. These side reactions resulted in the formation of a defective surface including a Se-rich surface and oxygen-related defects. Such negative effects can be overcome by adopting an etching strategy using potassium fluoride and myristic acid in combination. By overcoating a ZnS shell, blue emissive ZnSe/ZnS quantum dots with a maximum photoluminescence quantum yield of up to 91% were obtained. We further fabricated ZnSe quantum dots-based blue light-emitting diodes with an emission peak at 456 nm. The device showed a turn-on voltage of 2.7 V with a maximum external quantum efficiency of 4.2% and a maximum luminance of 1223 cd·m⁻².

We report an in-situ fabrication of halide perovskite (CH₃NH₃PbX₃, CH₃NH₃ = methylammonium, MA, X = Cl, Br, I) nanocrystals in polyvinylalcohol (PVA) nanofibers (MAPbX₃@PVA nanofibers) through electrospinning a perovskite precursor solution. With the content of the precursors increased, the resulting MAPbBr₃ nanocrystals in PVA matrix changed the shape from ellipsoidal to pearl-like, and finely into rods-like. Optimized MAPbBr₃@PVA nanofibers show strong polarized emission with the photoluminescence quantum yield of up to 72%. We reveal correlations between the shape of in-situ fabricated perovskite nanocrystals and the polarization degree of their emission by comparing experimental data from the single nanofiber measurements with theoretical calculations. Polarized emission of MAPbBr₃@PVA nanofibers can be attributed to the dielectric confinement and quantum confinement effects. Moreover, nanofibers can be efficiently aligned by using parallel positioned conductor strips with an air gap as collector. A polarization ratio of 0.42 was achieved for the films of well-aligned MAPbBr₃@PVA nanofibers with a macroscale size of 0.5 cm × 2 cm, which allows potential applications in displays, lasers, waveguides, etc.