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Perovskite quantum dots (PQDs) have shown great promise for use in photovoltaic devices, due to their ability to offer advantages such as tunability of visible light and efficient light emission. This study demonstrates the successful utilization of a triazine-based PO-T2T (2,4,6-Tris[3(diphenylphosphenyl)phenyl]-1,3,5-triazine; PO-T2T) as the electron transport layer (ETL) through an all-solution process. To improve the structural and optical characterization of CsPbBr 3 and CsPbI 3 QDs, three organic solvents, namely chlorobenzene, methyl acetate, and ethyl acetate, were selected to find an effective orthogonal solvent for PO-T2T. The all-solution processed devices incorporating PO-T2T and Methyl acetate (MeOAc) demonstrated impressive external quantum efficiencies of 5.57% for CsPbBr 3 and 1.60% for CsPbI 3 QDs. Notably, these devices also achieved the highest maximum luminance among all-solution processed PQDs-LEDs, with values of 33334 cd m–2 for CsPbBr 3 and 224 cd m–2 for CsPbI 3 QDs. [ABSTRACT FROM AUTHOR]

The utilization of perovskite quantum dots (PQDs) in photoelectric devices is indeed an area of intense research due to their advantageous properties such as tunability of visible light and efficient light emission. In this study, mixed CsPbI 3 and FAPbI 3 PQD dispersions were successfully employed for cation exchange to prepare red-color Cs 1−x FA x PbI 3 PQD with the photoluminescence (PL) wavelength from 689 nm (x = 0) to 778 nm (x = 1). It is also found that the aggregation of Cs 1−x FA x PbI 3 PQD films were strongly dependent on x. When x from 0 to 0.6, the holes in PQD thin films were gradually improved. On the opposite, when x > 0.6, the PQDs thin films returned more and more holes due to an excess of FA + cations. The resulting Cs 1-x FA x PbI 3 PQD based light-emitting diodes (LEDs) also demonstrated tunable emission wavelengths, and it is worth mentioning that the maximum external quantum efficiency (EQE) of 11.22 % was achieved with an emission wavelength of 758 nm when x = 0.6. [ABSTRACT FROM AUTHOR]

Perovskite quantum dots (QDs) have showed excellent optoelectronic properties to extend the application range of novel solid-state lighting, such as perovskite QD based LEDs (QD-LEDs). However, the traditional device structure of perovskite QD-LEDs employed PEDOT:PSS as a hole inject layer (HIL), which impairs stability due to acidic surface characteristics. This study proposes the sputtered NiO films as an HIL to replace acidic PEDOT:PSS. The NiO films with significantly different characteristics were prepared by controlling the sputtering parameters to investigate the devices' performance of NiO-based CsPbBr3 QD-LEDs. The optimized device showed an excellent performance with maxima luminescence of 20,118 cd/m2 and an external quantum efficiency (EQE) up to 3.63%. [ABSTRACT FROM AUTHOR]

This work reports warm white light-emitting diodes (WLEDs) using organic–inorganic halide perovskite materials coated YAG:Ce 3+ phosphors by a liquid phase synthesis method. The perovskite MAPbBr 3−x I x -coated YAG:Ce 3+ phosphors have more red light contribution than YAG:Ce 3+ phosphors without the perovskite coating. The chromaticity coordinate of white LED with YAG:Ce 3+ remote phosphor is (x = 0.3134, y = 0.3497) 6359. However, those of MAPbBr 2.5 I 0.5 and MAPbBr 2.0 I 1.0 -coated YAG:Ce 3+ remote phosphor shift to (x = 0.4220, y = 0.3725) 2908 and (x = 0.4067, y = 0.4028) 3525, respectively. The colors of perovskite-coated samples are more red and warm. Therefore, the perovskite-coated YAG:Ce 3+ method is useful for warm WLED. [ABSTRACT FROM AUTHOR]

One option for low-cost white light-emitting diodes (LEDs) is the combination of a near-ultraviolet (UV) LED chip (382 nm) and a single phosphor. Such MnY(MoO) single phosphors have been fabricated by a simple solid-state reaction route and their emission color tuned by controlling the Mn doping amount. The chromaticity coordinates of the white light emitted by the UV GaN LED with the MnY(MoO) phosphor were x = 0.5204 and y = 0.4050 [correlated color temperature (CCT) = 7958 K]. [ABSTRACT FROM AUTHOR]

• A ligand-exchange reaction using TOAB was present for stable CsPbI 3−x Br x quantum dots. • TOAB-passivated QDs showed environmental resistance, such as, moisture, light, and heat. • TOAB-passivated devices exhibited a maximum luminescence of 1345 cd/m2 and a maximum external quantum efficiency of 11.7%. In this study, we demonstrate a ligand-exchange reaction using tetraoctylammonium bromide (TOAB) salts for the as-synthesized CsPbI 3 perovskite nanoparticles (NPs) to ensure NPs with stable and improved device performance. TOAB passivation provides a negatively polarized halide-rich surface, higher steric hindrance, and a small amount of Br− anions in the NP lattice to significantly improve the NP stability. The red NP-based light-emitting diodes (NpLEDs) based on TOAB-passivated NPs also exhibited excellent performance because of shorter ligands and stable NPs, with a maximum luminescence of 1345 cd/m2 and a maximum external quantum efficiency of 11.7%. [ABSTRACT FROM AUTHOR]

Abstract: Al-doped ZnO (AZO) films with a thickness of ∼400nm were prepared by sputtering on glass substrates for use as transparent anodes of organic light-emitting diodes (OLED) devices. The operation voltages (at 100cd/m2) of OLED devices with AZO and ITO anode materials were 10.5 and 5.5V, respectively. The maximum luminance output of the AZO device was 6450cd/m2 (achieved at 12.5V) and that of the ITO device was 9830cd/m2 (achieved at 10.5V). We demonstrate that a hole-only device method can be used to estimate the suitability of AZO and ITO anodes in the OLED devices and to verify experimental results. The AZO thin films with low price and non-toxicity may be suitable as alternative anodes in OLED devices under high voltage. [Copyright &y& Elsevier]

Hybrid organic−inorganic and all-inorganic metal halide perovskite nanoparticles (PNPs) have shown their excellent characteristics for optoelectronic applications. We report an atmospheric process to embed formamidinium CH(NH2)2PbI3 (FAPbI3) PNPs in silica protective layer at room temperature (approximately 26 °C) employing (3-aminopropyl) triethoxysilane (APTES). The resulting perovskite nanocomposite (PNCs) achieved a high photoluminescence (PL) quantum yield of 58.0% and good stability under atmospheric moisture conditions. Moreover, the PNCs showed high PL intensity over 1 month of storage (approximately 26 °C) and more than 380 min of PNCs solutions in DI water. The studied near-infrared (NIR) light-emitting diode (LED) combined a NIR-emitting PNCs coating and a blue InGaN-based chip that exhibited a 788 nm electroluminescence spectrum of NIR-LEDs under 2.6 V. This may be a powerful tool to track of muscle and disabled patients in the detection of a blood vessel. [ABSTRACT FROM AUTHOR]

Organic light-emitting diodes (OLEDs) have developed rapidly in recent years. Thermally activated delayed fluorescent (TADF) molecules open a path to increase exciton collection efficiency from 25% to 100%, and the solution process provides an alternative technology to achieve lower cost OLEDs more easily. To develop commercial materials as exciplex hosts for high-performance and solution-processed OLEDs, we attempted to use 4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine (TAPC), poly(9-vinylcarbazole) (PVK), N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB), and poly(N,N'-bis-4-butylphenyl-N,N'-bisphenyl)benzidine (Poly-TPD) as the donors and 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (POT2T) as the acceptor to obtain the TADF effect. All donors and the acceptor were purchased from chemical suppliers. Our work shows that excellent TADF properties and high-efficiency exciplex OLEDs with low turn-on voltage and high luminance can be achieved with a simple combination of commercial materials. [ABSTRACT FROM AUTHOR]

In this study, the performances of red CsPbI3-based all-inorganic perovskite quantum-dot light-emitting diodes (IPQLEDs) employing polymeric crystalline Poly(3-hexylthiophene-2,5-diyl) (P3HT), poly(9-vinycarbazole) (PVK), Poly(N,N′-bis-4-butylphenyl-N,N′-bisphenyl)benzidine (Poly-TPD) and 9,9-Bis[4-[(4-ethenylphenyl)methoxy]phenyl]-N2,N7-di-1-naphthalenyl-N2,N7-diphenyl-9H-fluorene-2,7-diamine (VB-FNPD) as the hole transporting layers (HTLs) have been demonstrated. The purpose of this work is an attempt to promote the development of device structures and hole transporting materials for the CsPbI3-based IPQLEDs via a comparative study of different HTLs. A full-coverage quantum dot (QD) film without the aggregation can be obtained by coating it with VB-FNPD, and thus, the best external quantum efficiency (EQE) of 7.28% was achieved in the VB-FNPD device. We also reported a standing method to further improve the degree of VB-FNPD polymerization, resulting in the improved device performance, with the EQE of 8.64%. [ABSTRACT FROM AUTHOR]

This work presents a method for obtaining a color-converted red light source through a combination of a blue GaN light-emitting diode and a red fluorescent color conversion film of a perovskite CsPbI3/TOPO composite. High-quality CsPbI3 quantum dots (QDs) were prepared using the hot-injection method. The colloidal QD solutions were mixed with different ratios of trioctylphosphine oxide (TOPO) to form nanowires. The color conversion films prepared by the mixed ultraviolet resin and colloidal solutions were coated on blue LEDs. The optical and electrical properties of the devices were measured and analyzed at an injection current of 50 mA; it was observed that the strongest red light intensity was 93.1 cd/m2 and the external quantum efficiency was 5.7% at a wavelength of approximately 708 nm when CsPbI3/TOPO was 1:0.35. [ABSTRACT FROM AUTHOR]

In this paper, a thermally crosslinkable 9,9-Bis[4-[(4-ethenylphenyl)methoxy]phenyl]-N2,N7-di-1-naphthalenyl-N2,N7-diphenyl-9H-fluorene-2,7-diamine (VB-FNPD) film served as the hole transporting layer (HTL) of perovskite CsPbBr3 quantum-dot light-emitting diodes (QD-LEDs) was investigated and reported. The VB-FNPD film crosslinked at various temperatures in the range of 100~230 °C followed by a spin-coating process to improve their chemical bonds in an attempt to resist the erosion from the organic solvent in the remaining fabrication process. It is shown that the device with VB-FNPD HTL crosslinking at 170 °C has the highest luminance of 7702 cd/m2, the maximum current density (J) of 41.98 mA/cm2, the maximum current efficiency (CE) of 5.45 Cd/A, and the maximum external quantum efficiency (EQE) of 1.64%. Our results confirm that the proposed thermally crosslinkable VB-FNPD is a candidate for the HTL of QD-LEDs. [ABSTRACT FROM AUTHOR]

All inorganic perovskite quantum dots (PQDs) and perovskite CsPbX 3 /SiO 2 nanocomposites (PNCs) have shown their potentials for optical and lighting applications. We demonstrate a one-step approach to synthesize PQDs and PNCs more simply and effectively at room temperature in the open air. The resulting PNCs can show a narrow emission in the PL spectra and high stability under ambient conditions. In particular, both green CsPbBr 3 /SiO 2 and red CsPbI 3-x Br x /SiO 2 PNCs can be obtained by employing this easy and low-cost method. Even, the SiO 2 protection can also effectively prevent the halide exchange reaction between green and red PNCs, meaning the capability for white light applications. The resulting white light-emitting diodes (WLEDs) based on the green and red PNCs coated on the blue LED have a white Commission Internationale del' Enclairage (CIE) coordinates of (0.375, 0.362) and a low correlated color temperature (CCT) of 4054 K. [ABSTRACT FROM AUTHOR]