Recently, perovskite quantum dots
(QDs) have attracted intensive
interest due to their outstanding optical properties, but their extremely
poor chemical stability hinders the development of the high-performance
perovskite QD-based light-emitting diodes (PeLEDs). In this study,
chemically stable SiO2-coated core–shell perovskite
QDs are prepared to fabricate all-solution-processed PeLEDs. When
the SiO2 shell thickness increases, the chemical stability
of perovskite QDs is dramatically improved, while the charge injection
efficiency is significantly decreased, which becomes the biggest obstacle
for PeLED applications. Thus, controlling the SiO2 thickness
is essential to obtain core–shell perovskite QDs optimal for
PeLEDs in an aspect of chemical and optoelectrical properties. The
3-aminopropyl-triethoxysilane (APTES)/oleylamine (OAm) volume ratio
is found to be a critical factor for obtaining an ultrathin SiO2 shell. Optimization of the APTES/OAm ratio affords A-site-doped
CsPbBr3 QDs with an ultrathin SiO2 shell (A-CsPbBr3@SiO2 QDs) that exhibit longer radiative lifetimes
and smaller shallow trap fraction than those without A-site doping,
resulting in a higher photoluminescence quantum yield. A-CsPbBr3@SiO2 QDs also demonstrate long-term superior chemical
stability in polar solvents without loss of optical properties due
to passivation by the SiO2 shell and less defects via A-site
doping. Consequently, all-solution-processed PeLED is successfully
fabricated under ambient conditions, facilitating perovskite QD utilization
in low-cost, large-area, flexible next-generation displays.
Perovskite quantum dot (QD) light‐emitting diodes (PeLEDs) are ideal for next‐generation display applications because of their excellent color purity, high efficiency, and cost‐effective fabrication. However, developing a technology for high‐resolution multicolor patterning of perovskite QDs remains challenging, owing to the chemical instability of these materials. To overcome these issues, in this work, the generation of surface defects is prevented by controlling the ligand‐binding kinetics using a stable ligand system (Stable LS). The crystalline reconstruction of perovskite QDs after addition of the Stable LS results in an ≈18% increase in their photoluminescence quantum yield in solution and it also improves the ambient stability of the perovskite QD solution. Moreover, the perovskite QDs with Stable LS can undergo cross‐linking under UV irradiation. The tightly bridged perovskite QDs effectively prevent moisture‐assisted ligand dissociation in film state due to the increased hydrophobicity and restricted movement of the cross‐linked surface ligands. Thus, the cross‐linked perovskite QD film shows improved chemical/environmental stability without substantial deterioration in optoelectrical properties. As a result, a white electroluminescent device with high resolution (≈1 μm) is successfully fabricated by inkjet printing using green and red perovskite QDs.
Perovskite quantum dots (QDs) have been extensively studied as emissive materials for next-generation optoelectronics due to their outstanding optical properties; however, their structural instabilities, specifically those of red perovskite QDs,...
The addition of small quantities of a Bi surfactant is shown to have dramatic effects on the microstructure of GaAsSb alloys grown by organometallic vapor phase epitaxy (OMVPE). Epilayers grown without Bi show weak atomic ordering in plan-view selective area electron diffraction measurements, with periodicity of three or six times the [110] lattice spacing as previously reported. The addition of Bi at a ratio of 1% Bi∕Ga to the gas flow results in the appearance of strong CuAu and chalcopyrite ordering, as determined from electron diffraction measurements in both undoped, and heavily carbon doped layers. High-resolution, transmission electron microscopy lattice images clearly show the coexistence of {100}, {210} ordered and disordered structures with domain sizes of ∼10–20nm. Photoluminescence shows no band gap changes in GaAsSb samples with and without {100} and {210} ordering.
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