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The "Nobel Prize in Chemistry 2023" is awarded to Moungi G. Bawendi, Louis E. Brus, and Alexey I. Yekimov for discovering and synthesizing Quantum Dots (QDs). Colloidal QDs possess fascinating size‐, morphological‐, composition‐, and assembly‐tunable electronic and optical properties, which makes them star materials for various optoelectronic applications, especially as luminescent materials for next‐generation wide color gamut ultra‐high‐definition displays. Perovskite QDs (PQDs) have gained widespread attention in recent years. In less than ten years, research on perovskite‐related materials and devices has basically been perfected in terms of quantum yield and external quantum efficiency (EQE). However, on the eve of its industrial application, some key technical indicators and technical processes need to be met and resolved. The development and transformation of QD materials and then focuses on the progress of luminescence linewidth and EQE of the PQD light‐emitting diode. Finally, several application avenues are reviewed for PQDs, and some challenges and opportunities in the field are proposed. [ABSTRACT FROM AUTHOR]

Metal halide perovskite nanocrystals (NCs) have been widely studied for application in photonics and optoelectronics due to their excellent photoelectric properties. Perovskite NCs with narrow luminescence linewidth and high photoluminescence quantum yield are excellent assembly modules for building large-scale NC superlattices. The coupling of optics and electricity in such excellent aggregates gives them exceptional collective photoelectric performance, such as superfluorescence, red-shifted emission, coupling-enhanced electron transport, etc. Perovskite NC superlattices are expected to become another hot research topic in optoelectronics. Here, we focus on the collective behavior of superlattices and review the recent progress of the self-assembly, collective photoelectric properties, and applications of perovskite NC superlattices. Finally, a few challenges and prospects are indicated. [ABSTRACT FROM AUTHOR]

Inorganic perovskite quantum dots (QDs) have natural advantages in the field of light‐emitting diodes (LEDs) because of their high color purity and tunability in a wide range. However, when manufacturing efficiently mixed‐anion perovskite QDs (CsPbBrxI3−x) to meet the requirements of the pure red color standard in the display field (≈630 nm), results are difficult to control accurately due to the lack of exploration of its microscopic mechanism. Here, a microdynamics model is constructed for anion exchange dominated by vacancies which revealed the key role of polar solvent in reducing the surface energy barrier of anions through first‐principle calculations. Besides, a polar solvent construct in situ anion exchange channels method is proposed. Then, the precise control of anion exchange is demonstrated, and the precise regulation spectrum of the whole red‐light range (600–680 nm) is achieved. Finally, various QD LEDs (QLEDs) based on these tunable QDs are fabricated and exhibit excellent photoelectric performance in the main red range (620–680 nm). Among them, the champion QLEDs, have peak external quantum efficiency (EQE) of 16.3% at 633 nm and peak EQE of 18.2% at 646 nm, showing potential in meeting the requirements of display standard. [ABSTRACT FROM AUTHOR]

Halide perovskites have been one of the most promising research hotspots in the optoelectronic field. Recently, the issue of ion migration has been proved to be of great significance to their long-term stability and performance of optoelectronic devices. However, the stability of perovskite Cs2SnX6 (X = I, Br, Cl) under the light or electric field conditions has not been explored. In this work, we reported halide ion migration in lead-free all‐inorganic perovskite Cs2SnX6. The calculated formation energy to some degree reveals the concentration of the halide vacancy, which provides the favorable conditions for halide ion migration. Importantly, the theoretical long-term ion migration barriers are investigated to be higher than 1.00 eV, indicating they are relatively stable compared to CsPbX3, and the computational result matches the experimental result with the Nernst−Einstein relation that we adopted. The halogen ion migration energy barrier is 0.91 eV under the bias of 5 V, indicating that the perovskite Cs2SnX6 is relatively stable under a certain electric field. Furthermore, the experimental comparison of XRD results demonstrate that perovskite Cs2SnX6 has no obvious ion migration under certain light conditions. Finally, the analysis results show the Sn–X bond strength that explains the cause of such high barriers. These results reveal the migration mechanism of halide ions and provide new impetus for their optoelectronic applications. [ABSTRACT FROM AUTHOR]

Colloidal halide perovskite (CHP) quantum dots (QDs)/nanocrystals (NCs) have superior optoelectronic properties, such as high optical absorption coefficient, high photoluminescence quantum yield (PLQY), tunable bandgap, composition‐related luminescence, and low manufacturing cost, which have been considered as promising low‐dimensional semiconductor materials. Profiting from these unique characteristics, CHP NCs could be widely used in various optoelectronic devices, including light‐emitting diodes (LEDs), photodetectors (PDs), solar cells (SCs), and lasers. Synthesis is the basis for the wide use of CHP NCs, which plays a vital role in the research, development and application of CHPs. Therefore, we summarize the recent synthetic strategies, and their influencing factors (e. g. the effects of ligands, and anion exchange). Besides, a summary of their optoelectronic applications is plainly mentioned. Finally, we make a brief prospect and summarize the current problems and possible solutions of this area. [ABSTRACT FROM AUTHOR]

Light harvesting (LH) and carrier transport abilities of a photoactive layer, which are both crucial for optoelectronic devices such as solar cells and photodetectors (PDs), are typically hard to be synergistically improved. Taking perovskite as an example, a freeze-drying recrystallization method is used to construct porous films with improvements of both LH and carrier transport ability. During the freeze-drying casting process, the rapid solvent evaporation produces massive pores, the sizes of which can be adjusted to exploit the Mie scattering for enhancement of the LH ability. Meanwhile, owing to the strong iconicity, the interface between perovskite nanocrystals fused during recrystallization, which favors carrier transport. Subsequently, PDs based on these Mie porous and interface-fused films show a high on/off ratio of more than 104 and an external quantum efficiency value of 658 % under 9 V bias and 520 nm light irradiation. [ABSTRACT FROM AUTHOR]

Abstract: An investigation into the phase stabilities of CaTiO3 under high pressure was conducted using first-principles calculations based on density functional theory. We have identified three candidate structures of CaTiO3, Pbnm, Pm3m and Cmcm, respectively. Our results demonstrate that a phase transition from orthorhombic (Pbnm) to cubic (Pm3m) is impossible for CaTiO3 under high pressure at ambient temperature, and further predict that Pbnm-CaTiO3 will transform to post-perovskite phase (Cmcm) at enough temperature and pressure. [Copyright &y& Elsevier]

Quantum-dot-based light-emitting diode (QLED) with simultaneously improved efficiency and operational lifetime is achieved through charge balance engineering using a bilayered electron transport structure. The modulated device exhibits a color-saturated green emission, a low turn-on voltage of 2.0 V, a peak EQE of 21.63 per cent, and an operational lifetime of 1.15 h under an initial luminance of 4064 cd/m2, which is among the best-performing perovskite LEDs demonstrated so far. Perovskite quantum-dot-based light-emitting diodes (QLEDs) are highly promising for future solid-state lightings and high-definition displays due to their excellent color purity. However, their device performance is easily affected by charge accumulation induced luminescence quenching due to imbalanced charge injection in the devices. Here we report green perovskite QLEDs with simultaneously improved efficiency and operational lifetime through balancing the charge injection with the employment of a bilayered electron transport structure. The charge-balanced QLEDs exhibit a color-saturated green emission with a full-width at half-maximum (FWHM) of 18 nm and a peak at 520 nm, a low turn-on voltage of 2.0 V and a champion external quantum efficiency (EQE) of 21.63%, representing one of the most efficient perovskite QLEDs so far. In addition, the devices with modulated charge balance demonstrate a nearly 20-fold improvement in the operational lifetime compared to the control device. Our results demonstrate the great potential of further improving the device performance of perovskite QLEDs toward practical applications in lightings and displays via rational device engineering. [ABSTRACT FROM AUTHOR]