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Solution-processed perovskite light-emitting diodes (PeLEDs) show great potential for low-cost fabrication of large-area display panel, however, large crystallinity and poor film coverage generally cause high operating voltage and low luminescence efficiency in all solution-processed PeLEDs, and thus limiting their commercial applications. Here, the phenylpropylammonium bromide (PPABr) as ligand additive in MAPbBr 3 for improving perovskite film quality and the device performance of PeLEDs are reported. With varying additive ratios of PPABr, the morphological changes and photoluminescence properties of perovskite film were investigated. Benefiting from precisely managing the ratio, the PPABr-based perovskite films exhibited well-defined crystal phase and high photoluminescence intensity. As a result, all solution-processed MAPbBr 3 PeLEDs with the optimized concentration of PPABr showed a low turn-on voltage of 2.2 V and a maximum device luminance of 13,666 cd/m2, which are comparable to the non-additive device (with turn-on voltage and luminance of 3.0 V and 2910 cd/m2). Notably, an approximately 5.5-fold improvement for 0.09 mol PPABr-based device in current efficiency was achieved compared to the pristine MAPbBr 3 PeLED. High performance all solution-processed perovskite light-emitting diodes by incorporating long ligand the phenylpropylammonium bromide as additives into MAPbBr3 layer. [Display omitted] • High performance all solution-processed PeLEDs were designed and fabricated. • PPABr as additives for MAPbBr 3 significantly enhance the crystalline phase and PL properties of thin film. • State-of-the-art MAPbBr 3 PeLEDs exhibited ultra-low turn-on voltage of 2.2 V. • An approximately 5.5-fold improvement in current efficiency was achieved for the PPABr-based device. [ABSTRACT FROM AUTHOR]

A new family of bipolar fluorinated 3,3′-dimethyl-9,9′-bianthracene derivatives (MBAnFs) have been synthesized, characterized and applied as deep-blue emitters and host materials in fluorescent organic light-emitting devices (OLEDs). Fine tuning the emission characteristics could be achieved by varying the position and the number of the F substituents on the two phenyl rings attached to MBAn core. Remarkably, 10,10′-bis(4-fluorophenyl)-3,3′-dimethyl-9,9′-bianthracene (MBAn-(4)-F)-based OLEDs showed an excellent performance. Both non-doped and doped multilayer OLEDs based on MBAn-(4)-F achieved the maximum external quantum efficiency (EQE max ) of 6.11% and 6.65% with Commission Internationale de L'Eclairage (CIE) coordinates of (0.155, 0.058) and (0.153, 0.055), respectively, matching the requirement of European Broadcasting Union standard of CIE (0.15, 0.06) very well. Furthermore, when doping blue-emitting p -bis( p -N,N-diphenyl-aminostyryl)-benzene (DSA-ph) into MBAn-(4)-F as a light-emitting layer (EML), the device achieved an astonishing current efficiency of 23.01 cd A −1 and a record-setting EQE of 11.52% with negligible efficiency roll-off, compared with other DSA-ph-based OLEDs. These results are attributed to the well-controlled bipolar characteristic of the MABn-(4)-F, leading to a better charge balance in the EML. In addition, the combination of the locally emissive component and twisted intramolecular charge-transfer component in one excited state can significantly enhance the singlet generation fraction in OLEDs. [ABSTRACT FROM AUTHOR]

Abstract: The carrier transfer and luminescence characteristic of concentration-dependent tris(2-phenylpyridine) iridium (Ir(ppy)3) doped in 4,4′-bis(carbazol-9-yl)-biphenyl (CBP) film of 40nm have been investigated. Based on the charge-only devices with different concentration of Ir(ppy)3:CBP, we have found that an increasing dopant concentration can facilitate hole transfer, whereas suppress electrons transfer reversely. The ratio of Ir(ppy)3 in CBP plays a significant role in energy transfer process. Results have shown that excess Ir(ppy)3 possessed a shortened fluorescence lifetime, indicating a concentration quenching effect in Ir(ppy)3:CBP film. The performance of the device decreased rapidly with increasing of doping concentration of Ir(ppy)3 in CBP. A high efficiency of 65.2cd/A with low efficiency roll-off phosphorescent OLED was achieved, in which 10wt%Ir(ppy)3 in CBP was light-emitting layer. [Copyright &y& Elsevier]

[Display omitted] • In 2 O 3 film is used as an electron transport layer in Perovskite Solar Cells. • The In 2 O 3 electron transport layer is prepared by electron beam evaporation. • In 2 O 3 layer can improve the film formation quality and crystallinity of perovskite. • The photovoltaic performance of perovskite solar cells is enhanced by In 2 O 3 layer. In perovskite solar cells, the interface plays a crucial role in photovoltaic performance because excitons dissociate and compound at the interface. In this paper, the optical absorption layer of In 2 O 3 planar perovskite solar cells is studied, which is an efficient intermediate layer between the TiO 2 electron transport layer and perovskite. The modification of the In 2 O 3 interlayer increases the average power conversion efficiency from 6.74% to 10.68%. Based on this background, some other feature descriptions are also carried out. The results show that the photovoltaic performance can be improved by depositing the In 2 O 3 interlayer, mainly due to the improved film morphology, reduced recombination center, bulk carrier concentration and Hall mobility. It has been shown that In 2 O 3 can be used as an efficient interface material on all-inorganic perovskite solar cells. [ABSTRACT FROM AUTHOR]

Abstract The development of white organic light-emitting diodes (WOLEDs) holds great promise for the production of high-color-quality lighting sources. High quantum efficiencies for the conversion of electrical energy to light have been realized. The color stability and color-rendering index (CRI) become bottleneck for the commercial application of WOLEDs. Here, we employed a metal-free dimerization of 1‑phenyl‑3,5‑diamine‑triazine (DPDT) as a single non-doped emitter in WOLEDs, that exhibits mild efficiency roll-off while maintaining CRI of 92. This high CRI is attributable to the DPDT with efficient monomer and excimer emission, which together emit a relatively wide spectrum that nearly covers the entire range of visible light. The formation of the excimer can make the emission color of single-emitter based WOLEDs tunable with the applied bias over a wide range from blue to pure white. Highlights • The metal-free dimerization of 1-phenyl-3,5-diamine-triazine (DPDT) materials were synthesized. • The emission color can be tuned over a wide range from blue to pure white. • The resulting color tunable WOLEDs achieves mild efficiency roll-off while maintaining CRI of 92. [ABSTRACT FROM AUTHOR]

Abstract A series of alkyl substituted 9,9′-bianthracene derivatives (BAs) with easy availability and low cost have been applied as deep-blue emitters and blue host materials in fluorescent organic light-emitting diodes (OLEDs). The nearly perpendicular geometry configuration of 9,9′-bianthracene and the additional alkyl units with large steric hindrance in methyl substituted MBA and tert- butyl substituted TBBA would reduce the aggregation formation emitting at longer wavelength by intramolecular and intermolecular interaction, which endows both of the compounds with good thermal properties, and film-forming abilities as well as excellent electroluminescence performance. Nondoped pure deep-blue OLED using TBBA as the emitter showed good performance with EQE of 3.20% and high color purity with CIE (0.15, 0.06), which matched the EBU standard blue very well. Furthermore, these BAs worked as excellent host materials for p -bis(p - N,N -diphenyl-aminostyryl)benzene (DSAph) dopant to get high-performance OLEDs with low turn-on voltages and high efficiencies, especially for MBA bearing two methyl substituents at 3- and 3′-positions of the 9,9′-bianthracene as the fluorescent host with a low turn-on voltage of 3.0 V, a high current efficiency of 16.54 cd/A and a high EQE of 9.47% with unobservable efficiency roll-off. Particularly, EQE can be maintained over 9.20% with very little variation of 0.54% in the range of luminance value of 1.54–13800 cd/m2 for the MBA-based device. The improved EQEs are due to the enhanced occurrence of singlet excitons in BAs-based devices. Graphical abstract Image 1 Highlights • Alkyl substituted 9,9'-bianthracene derivatives (BAs) with easy availability and low cost. • Nondoped TBBA-based blue OLED showed EQE of 3.20% with excellent CIE (0.15, 0.06). • EQE maintained over 9.24% with very little variation of 0.54% in the range of luminance 1.54–13800 cd/m2 for MBA:DSAph-based device. [ABSTRACT FROM AUTHOR]

Abstract Top-emission flexible organic light-emitting devices (TE-FOLEDs) are highly suitable for next generation display due to their numerous assets including top-emitting configuration and mechanical flexibility. One major challenge in TE-FOLEDs is to prepare a deformable and reflective bottom electrode capable of effective carrier injection. In this paper, a new strategy for efficient and foldable TE-FOLEDs is demonstrated. It is based on a highly conductive Ag-nanoparticles (Ag-NPs) modified graphite that is used as a flexible bottom electrode. The good reflectance to full-color emission (>59% over the whole visible wavelength range), ultralow sheet resistance (<5 Ω/sq), and high tolerance to mechanical bending (almost unchanged in resistance after bending 1000 times with an angle of ±90°) of the modified graphite synergistically constitute a breakthrough in the domain of TE-FOLEDs. The maximum current efficiencies reach 15.0, 50.2, 16.8 cd/A for red, green, blue emissions, respectively. Colorimetric gamut increased by 99.6% compared to bottom emission structure with the corresponding Commission Internationale de L'Eclairage (CIE) coordinates of the red/green/blue (R/G/B) devices. In particular, the TE-FOLEDs incorporating highly flexible graphite electrodes offer great mechanical durability and the initial brightness of 5000 cd/m can be maintained over 90% after bending for 1000 bending cycles. This approach is expected to open a new avenue for developing foldable displays. Graphical abstract Image 1 Highlights • The Ag nanoparticles modified graphite onto PET substrate was fabricated with high flexibility and good heat dissipation. • The R/G/BTE-FOLEDs exhibit high color purity and enhanced colorimetric gamut compared to bottom-emitting devices. • The high current efficiency of 15.0, 50.2 and 16.8 cd/A were achieved for R/G/B TE-FOLEDs with low efficiency roll-off. • The TE-FOLEDs show high flexibility after bending for 1000 cycles at the initial brightness of 5000cd/m2. [ABSTRACT FROM AUTHOR]

White organic light-emitting diodes (WOLED) with inorganic/organic/hybrid nanolaminate distributed Bragg reflector (DBR) prepared by atomic layer deposition (ALD) has been firstly developed, and the improved structural, optical, and electrical properties have been observed. The functional layer consists of periodically alternating layers of ZrO 2 /Zircone (zirconium alkoxides with carbon-containing backbones) films fabricated using ALD. By well adjusting the thickness and emissive dyes of the emission layer, three white light diodes were realized based on three cavity modes with different resonance wavelength and intensity. The narrowed lectroluminescent (EL) spectra from the microcavity organic light emitting diodes (MOLEDs) are of high-purity, and the off-resonant optical mode is highly suppressed due to the excellent optical properties of the DBR layers with high reflectivity in a wide stop-band range. The CIE chromaticity coordinates of devices are tuned from (0.33, 0.34), (0.43, 0.40) to (0.57, 0.40), which are all on the planckian locus, and the color temperature is adjusted from 5783 K, 3842 K to 2245 K. This work exhibits a simple and novel approach to achieve a sunlight-like WOLED by constructing the inorganic/organic nanolaminate DBR using ALD, which will be very important for healthy display and lighting. [ABSTRACT FROM AUTHOR]