Recently, all-inorganic perovskite quantum dots (PeQDs), CsPbX 3 have become attractive because of their excellent optoelectronic properties and superior air/moisture stabilities compared with conventional organic−inorganic hybrid perovskites, and the application of CsPbX 3 PeQDs to light-emitting devices (LEDs) has also become competitive. To enable the use of CsPbX 3 PeQDs for thin-film-type perovskite quantum-dot LEDs (PeQLEDs), a paradox associated with the ligand property and surface passivation must be overcome during thin-film fabrication. A decline in the photoemission performance was observed at relatively low amounts of surface-passivating ligands, while the quality of the thin film deteriorated in the presence of excessive ligands. To address this conflict, in this study, the performance of PeQLEDs based on CsPbX 3 fabricated by a novel method involving solid-state ligand exchange (SLE) with aromatic acid/amine was investigated. Using this strategy, most of the excess ligands were removed while preserving the surface passivation of CsPbX 3 in the thin film. We discovered that an optimal aromatic acid/amine ligand ratio is required for CsPbX 3 -based PeQLEDs to retain the solubility of the PeQDs and simultaneously accomplish the SLE process without affecting the properties of the PeQD. Moreover, an improvement in the overall photoemission efficiency of the resulting PeQLED device was confirmed under red, green, and blue conditions. In addition, a luminance of 1889 cd/m 2 and a current efficiency of 6.28 cd/A was achieved for the PeQLED.

Colloidal quantum dots can control the bandgap by controlling the particle size, and are capable of solution processing, which is cost competitive, and has a narrow half width of the emission wavelength.Using these characteristics, it is possible to utilize various kinds of LED, solar cell, and bio imaging.Among them, indium phosphide (InP) quantum dots have a bandgap capable of emitting light in the near-infrared region from the visible light region, and are less toxic to humans and the environment than cadmium-based quantum dots, and are attracting attention as next generation light emitting materials.However, the limited choice and high cost of P precursors have a negative impact on their practical applicability. In this work, I report the large-scale synthesis of highly luminescent InP@ZnS QDs from an elemental P precursor (P4), which was simply synthesized via the sublimation of red P powder. The size of the InP QDs was controlled by varying the reaction parameters such as the reaction time and temperature, and the type of In precursors. This way, the photoluminescence properties of the synthesized InP@ZnS QDs could be easily tuned across the entire visible range, while their quantum yield could be increased up to 60% via the optimization of reaction conditions. Furthermore, possible reaction pathways for the formation of InP QDs using the P4 precursor have been investigated with nuclear magnetic resonance spectroscopy and it was demonstrated that the direct reaction of P4 precursor with In precursor produces InP structures without the formation of intermediate species. The large-scale production of InP@ZnS QDs was demonstrated by yielding more than 6 g of QDs per onebatch reaction.In the case of InP using different precursor P except the Tris(Trimethylsilyl) phosphine ((TMS)3P) there has been a problem that the size distribution is poor. Two kinds of P precursors with different reactivities were used to separate the nucleation and growth processes and to induce growth along the Lamer mechanism to produce uniform particles. For this, (TMS)3P and DEAP were used as fast reacting P precursors, and P4 was used as a slow reacting P precursor. Through this, the possibility of uniform particle formation was observed. I strongly believe that the newly developed approach bears the potential to be widely used for manufacturing inexpensive high-quality QD emitters. Blank page Contents

This article focuses on state-of-the-art technologies used in the research on materials, devices and processes to achieve high-performance QD-LEDs.

Wavelength-selective harvesting by organic solar cells (OSCs) has attracted significant research attention due to the unique potential of these materials for smart photovoltaic window applications. Here, a visibly transparent OSC is demonstrated by utilizing both near-infrared (NIR)-absorbing polymer donor and nonfullerene acceptor (NFA) materials with narrow optical band gaps of less than 1.4 eV. Despite the substantial overlap in absorption spectra between the donor and acceptor, sufficient lowest unoccupied molecular orbital (LUMO) and highest occupied molecule orbital (HOMO) energy offsets for efficient charge separation with concurrent very low voltage losses yield a power conversion efficiency (PCE) of 9.13%. Moreover, with the introduction of an ultrathin Ag film (8 nm) as a transparent top electrode, semitransparent OSCs exhibit an excellent dual-side photovoltaic performance of 5.7 and 3.9% under bottom and top illumination, respectively, with high transmittance reaching 60% at wavelengths from 400 to 600 nm. This approach is expected to provide a new perspective in developing the highly efficient and transparent OSCs.

AbstractsQuantum dot light-emitting diodes (QD-LEDs) are considered as competitive candidate for next-generation displays or lightings. Recent advances in the synthesis of core/shell quantum dots (QDs) and tailoring procedures for achieving their high quantum yield have facilitated the emergence of high-performance QD-LEDs. Meanwhile, the charge-carrier dynamics in QD-LED devices, which constitutes the remaining core research area for further improvement of QD-LEDs, is, however, poorly understood yet. Here, we propose a charge transport model in which the charge-carrier dynamics in QD-LEDs are comprehensively described by computer simulations. The charge-carrier injection is modelled by the carrier-capturing process, while the effect of electric fields at their interfaces is considered. The simulated electro-optical characteristics of QD-LEDs, such as the luminance, current density and external quantum efficiency (EQE) curves with varying voltages, show excellent agreement with experiments. Therefore, our computational method proposed here provides a useful means for designing and optimising high-performance QD-LED devices.

This study explored the effect of zinc precursors on the optical properties of InP quantum dots (QDs) by controlling the reactivity of zinc carboxylates via a simple thermal treatment. The formation of zinc oxo clusters, Zn4O­(oleate)6 and Zn7O2(oleate)10, during the thermal decomposition of zinc oleate was confirmed by matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry. Using zinc oxo clusters as reaction precursors, high-quality InP QDs with a high photoluminescence quantum yield (PLQY) and a narrow full width at half-maximum (FWHM) were synthesized (green QDs: PLQY = 95%, FWHM = 37 nm; red QDs: PLQY = 84%, FWHM = 40 nm). The analysis results showed that improved optoelectronic properties were achieved by two important functions of the zinc oxo clusters: (1) suppressing the rapid depletion of the highly reactive phosphorus source and inducing size uniformity of the In­(Zn)P core, and (2) facilitating the formation of an oxidized buffer layer, which effectively controls defects. Likewise, the use of reactivity-controlled species is an effective strategy for the synthesis of well-designed QDs.

Blue indium phosphide quantum dot (InP QD) is an emerging colloidal semiconductor nanocrystal, considered as a promising next‐generation photoactive material for light‐emitting purposes. Despite the tremendous progress in blue InP QDs, the synthetic method for tailoring InP core size to realize the blue‐emissive QDs still lags behind. This work suggests a synthetic method for blue‐emitting InP QDs by engineering the core size with an incipient ZnS (i‐ZnS) shell. The formation of i‐ZnS complexes, before the tris(trimethylsilyl)phosphine injection (e.g., before core growth process), restrains the overgrowth of InP nuclei by rapidly forming a ZnS shell on its surface, thereby resulting in further dwarfed InP cores. With additional ZnS shell coating, the blue QDs exhibit a photoluminescence quantum yield of ≈52% at 483 nm. The origin of bandgap diminution with the increase of shell thickness, or with the utilization of ZnSe shell is unraveled via the first‐principles density functional theory simulations. Simulational evidence on InP‐core densification with the shell coating, along with accompanying changes in chemical and structural properties, is presented. The blue‐emitting InP QD device shows a maximum luminance of 1162 cd m−2 and external quantum efficiency of 1.4%.

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