Light-Emitting Transistors with High Color Purity Using Perovskite Quantum Dot Emitters.

Deep-red CsPbI3 perovskite quantum dots (PeQDs) are essential for high-efficiency perovskite light-emitting diodes (PeLEDs) because of their high color purity and high photoluminescence quantum yield (PLQY). The synergetic strategy of indium (In) doping and chlorine (Cl) surface passivation not only partially replaced Pb2+ ions with the smaller ionic In3+ but also filled I- vacancies by Cl- on the surface, maintaining the humidity stability for more than 24 days and yielding excellent PLQY. Benefiting from this synergetic strategy, deep-red (approximately at 683 nm) CsPbI3 PeLEDs showed a maximum luminance and external quantum efficiency (EQE) of 311 cd m-2 and 8.32%, respectively.

Complementary ligand decorated cesium lead bromide nanoplatelets for high performance light-emitting diodes

One-step preparation of excellent flexible ethyl cellulose composite film for LED

The past decade has witnessed the increasing interest in cesium lead halide perovskite quantum dots (PQDs) for their excellent optical properties with higher photoluminescence efficiency and tunable emission wavelengths widely applied in white LED, photovoltaic devices, etc. Here we report the preparation of CsPbBr3 PQDs by a facile anti-solvent method using conventional quaternary ammonium bromide (CTAB) as a double modifier-both proper alkyl group protection and bromine source donator. The as-formed PQDs are well-monodispersed cubes with a size of 10-15 nm and high photoluminescence quantum yield (PLQY) of up to 43 %. To enhance the stability of PQDs, CsPbBr3 @PS microspheres were formed by electrospraying process. The microspheres not only show excellent luminous properties, but exhibit much higher stability against air and UV light irradiation due to the super hydrophobic property of polystyrene.

Enhancing air-stability of CH3NH3PbBr3 perovskite quantum dots by in-situ growth in metal-organic frameworks and their applications in light emitting diodes

Lead halide perovskite quantum dots (PeQDs) are triggering a revolution in display technologies because of their near-unity photoluminescence quantum yield (PLQY), narrow band emission, wide tunable bandgap and facile synthesis. Therefore, they have been extensively investigated as color converters or emissive layers for light-emitting diode (LED) displays. However, the poor stabilities in the phase and structure of PeQDs make them hard to be practically applie, and the ultimate goal is therefore to improve the long-term stability of PeQDs. The poor stability of PeQDs originates from their inherent ionic nature. Under external conditions (such as light, heat, water and oxygen), PeQDs will decompose through interfacial reactions, leading to obvious fluorescence quenching. Although many efforts have been made to prepare robust PeQDs that are, to some extent, resistant to water, air, light, or heat exposure, he overall reliability of PeQDs shows limited improvement under the synergistic effects of multiple factors, which are usually the case in practical LED applications. We report ultrastable CsPbBr3:Sr/PbBr(OH)/molecular sieve composites (Fig. 1) with a high photoluminescence quantum yield of 75% and high overall stability when exposed to water, blue light and heat, owing to (i) the increased formation energy of CsPbBr3 PeQDs by Sr doping and (ii) good encapsulation by PbBr(OH) and molecular sieves. These composites maintain 54% of their initial intensity after being aged at 85°C and 150 mW/cm2 for 720 min, which is superior to commercial green CdSe-based QDs. These promising composites are then used to produce Mini-LED backlights with a high luminous efficacy of 86 lm/W and a color area of ~124% of the National Television Standards Committee or 93% of the Rec. 2020 standards by combining them with red CdSe/CdS/ZnS QDs and a blue Mini-LED chip. We believe that highly reliable PeQDs can be achieved by building well-designed composite structures, thus enabling them to be practically applied in emerging lighting and displays. Figure 1

Inorganic perovskite quantum dots (QDs) have attracted wide attention in display and solid-state lighting because of their easily tunable band-gaps and high photoluminescence quantum yields (PLQY) of green light emission. However, some drawbacks limit their practical applications, including the low PLQY of blue light emission and the instability in the moisture environment. In this work, efficient blue-light emitting CsPbBr3 perovskite QDs with PLQY of 72% were developed through a bandgap engineering approach. The achieved blue-light emitting PLQY is much higher than the values acquired in the inorganic perovskite QDs in the literature. And the emission color of the as-prepared QDs can be facially tuned by only adjusting the reaction temperature. Further, the mono-dispersed perovskite QDs@SiO2 composites were constructed benefiting from the low temperature synthesis. The optical performance of the QDs could be well persisted even in the moisture environment. Finally, the as-prepared QDs@SiO2 composite was fabricated as the QD ink on the anti-counterfeit printing technology, from which the obtained pattern would emit varied color under UV lamp. And the as-prepared composites was also applied for fabricating WLED, with Commission Internationale de l’Eclairage (CIE) color coordinates of (0.33, 0.38) and power efficiency of 32.5 lm W−1, demonstrating their promising potentials in solid-state lighting.

Approaching high-performance light-emitting devices upon perovskite quantum dots: Advances and prospects

Perovskite quantum dots (QDs) are emerging as one of the most promising candidates for the monochromatic light‐emitting diodes (LEDs) approaching the Rec. 2020 color gamut due to their extremely narrow emission bandwidth. Another important aspect are the high photoluminescence quantum yield (PLQY) values that can be obtained either in solution or thin films making these materials as promising candidates for optoelectronic applications such as LEDs or solar cells. Considerable research efforts in chemistry, chemical engineering, solid‐state physics, and material sciences have been made in the past years. The new opportunity in the field of semiconductor quantum dots is still in the beginning phase and is expected to remain active in the following years. Here, in this invited commentary, we briefly discuss and summarize the opportunities and challenges in both fundamental and technological aspects, based on our work and the recent work in this field.

Water-stable all-inorganic CsPb1-XSnXBr2I perovskite quantum dots encapsulated in paraffin for white light-emitting diodes

Currently, perovskite containing organometal halides have issues for limited color range and low photoluminescence (PL). In this regard, we designed split-ligand mediated re-precipitation (Split-LMRP) as a unique synthesis method for improved stability and PL by separating octylamine and oleic acid (OA), compared to a conventional method. [Accepted manuscript] Octylamine adjusted the size of the nucleus as main ligand, while OA acted only as a stabilizer. Especially, the QDs based on Split-LMRP remained PL intensity after 5 days with strong PL emission and a high PL quantum yield (PLQY) of 91.5% due to the removal of most polar solvents during re-precipitation. In addition, the size of the QDs was adjusted constantly in the range of 2-5 nm depending on the concentration of octylamine. When the perovskite QDs were used as the intermediate layer of the perovskite solar cell, performance and reproducibility of the PSC were improved by forming stable phases.

Bright red-emitting phosphors with high color purity and high photoluminescence quantum yield (PLQY) are highly demanded for the fabrication of high-performance warm-white light-emitting diodes (LEDs). Herein, we demonstrated a novel efficient Eu3+-activated Ca2LaHf2Al3O12 garnet phosphor with excellent luminescence properties for near-ultraviolet (near-UV) excited warm-white LEDs. The Ca2LaHf2Al3O12:Eu3+ phosphors exhibited an intense excitation spectrum in the near-UV region with a maximum around 394 nm, and they produced dazzling red luminescence peaking at 592, 614, 659, and 711 nm due to the 5D0 → 7FJ (J = 1-4) transitions of Eu3+ ions when the excitation wavelength was set at 394 nm. Luminescent properties have been studied as a function of Eu3+ doping concentration, and the highest emission intensity was achieved at 50 mol % Eu3+, while the dipole-dipole interaction brought the concentration quenching effect. The Ca2LaHf2Al3O12:50%Eu3+ sample exhibited CIE chromaticity coordinates of (0.6419, 0.3575) with a color purity of 92.7%, and its PLQY was measured to be 64%. The thermal stability and activation energy of Ca2LaHf2Al3O12:50%Eu3+ phosphors were also discussed and analyzed. Finally, we made a near-UV chip-based white LED device in which the Ca2LaHf2Al3O12:50%Eu3+ phosphor was utilized as a red ingredient. A bright warm-white light emission was realized from this LED device under 80 mA driving current, accompanied by a high color rendering index (CRI) of 88.3, a low correlation color temperature of 3853 K, and good CIE chromaticity coordinates of (0.3909, 0.3934). These results revealed that these red-emitting Ca2LaHf2Al3O12:Eu3+ phosphors have promising application prospect in near-UV-excited warm-white LEDs with high a CRI.

Highly stable CsPbBr3 perovskite quantum dots incorporated in aluminum stearate

Perovskite quantum dots (PQDs) are promising nanomaterials for optoelectronic and energy-conversion applications due to their high photoluminescence quantum yield, tunable bandgap, and defect tolerance. However, their soft ionic lattices exhibit dynamic disorder, anharmonic vibrations, and ion migration, leading to challenges in structural and optoelectronic stability. This review elucidates how molecular dynamics (MD) simulations decode the interplay of atomic fluctuations, lattice dynamics, and surface reconstruction in PQDs, revealing mechanisms governing their stability and performance. It highlights how multi-scale MD frameworks link femtosecond-scale atomic motions to microsecond-scale degradation processes, enabling predictive design of resilient PQDs. Key findings include the role of anharmonic lattice vibrations in defect tolerance, the impact of surface ligand dynamics on emission linewidth, and the mitigation of ion migration through matrix embedding, offering strategies for enhanced device reliability. Classical molecular dynamics (CMD) simulations employ Lennard-Jones, Buckingham, ReaxFF, and COMB3 force fields to model mesoscale phenomena, including ligand rearrangement and surface fusion. Ab initio molecular dynamics (AIMD) uses density functional theory (DFT) with PBE and HSE06 functionals, typically with plane-wave basis sets (e.g., PAW), to capture ion-electron coupling and lattice anharmonicity. Nonadiabatic molecular dynamics (NAMD) incorporates surface hopping to simulate ultrafast charge transfer. Machine-learning potentials, trained via neural networks and Gaussian processes, enhance sampling with metadynamics and replica-exchange techniques.

Owing to their large absorption cross-sections and high photoluminescence quantum yields, lead halide perovskite quantum dots (PQDs) are regarded as a promising candidate for various optoelectronics applications. However, easy degradation of PQDs in water and in a humid environment is a critical hindrance for applications. Here we develop a Pb-S bonding approach to synthesize water-resistant perovskite@silica nanodots keeping their emission in water for over six weeks. A two-photon whispering-gallery mode laser device made of these ultra-stable nanodots retain 80% of its initial emission quantum yield when immersed in water for 13 h, and a two-photon random laser based on the perovskite@silica nanodots powder could still operate after the nanodots were dispersed in water for up to 15 days. Our synthetic approach opens up an entirely new avenue for utilizing PQDs in aqueous environment, which will significantly broaden their applications not only in optoelectronics but also in bioimaging and biosensing.