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White-light emission is achieved from a single layer of diblock copolymer micelles containing green- and red-light-emitting dyes in the separate micellar cores and blue-light-emitting polymer around their periphery, in which fluorescence resonance energy transfer between fluorophores is inhibited due to micelle isolation, resulting in simultaneous emission of these three species. [ABSTRACT FROM AUTHOR]

Efficient multilayer white polymer light-emitting diodes (WPLEDs) with aluminum cathodes are fabricated. The multilayer structure is composed of a water soluble hole-injection layer, a toluene-soluble emissive layer, and an alcohol-soluble emissive layer. The polarity difference of the solvents used for spin coating these polymers allows for realization of the multilayer polymer structure. The recombination zone confined at the interface of the two emissive polymers avoids exciton quenching by electrodes, and white emission is realized by harvesting photons emitted from the two emissive polymers. A maximum luminous efficiency of 16.9 cd/A and a power efficiency of 11.1 lm/W are achieved for this WPLED. [ABSTRACT FROM AUTHOR]

Nonfullerene acceptors are currently dominating the research and development of organic photovoltaics (OPVs). Exploring the charge separation mechanism is helpful to understand the photovoltaic process in efficient nonfullerene-based OPVs. Herein, we have selected two typical acceptors: PC 71 BM and nonfullerene acceptor IT-M, and have studied the device function and the ultrafast charge carrier dynamics in the PBDB-TF:IT-M and PBDB-TF:PC 71 BM blends to investigate how they are affected by different blend morphologies induced by using a popular solvent additive 1,8-diiodooctane (DIO). It is found that ultrafast charge generation occurs in both of the two blend systems. For the IT-M blend film, the DIO additive strongly affects the ultrafast photophysical process. Efficient hole transfer is observed for the IT-M blend processed with DIO compared to the pristine IT-M blend. Moreover, the charge density is significantly increased in the DIO-processed IT-M blend film. In contrast to the IT-M blend, the DIO does not strongly affect the ultrafast charge carrier dynamics in PC 71 BM blend possibly due to its slight effect on the blend morphology. The reionization of spin-triplet charge transfer states can occur faster than relaxation to triplet in both of the well-ordered blend film processed with DIO resulting in an enhanced current density and fill factor. Image 1 • Ultrafast charge separation is observed in both PBDB-TF:IT-M and PBDB-TF:PC 71 BM blend films. • Efficient hole transfer occurs and the charge density is significantly increased in DIO-processed PBDB-TF:IT-M blend film. • The reionization of 3CT states can occur faster than relaxation to triplet excitons in both fullerene and nonfullerene blend films processed with DIO. [ABSTRACT FROM AUTHOR]

Solution-processed organic light-emitting diodes (s-OLEDs) have received a great deal of interest owing to the huge market application potentials as large-size, flexible, high-quality self-luminous display panels and lighting sources. It is anticipated that those electronic products can be easily manufactured by modern wet-processing techniques, e.g. ink-jet printing and 'roll-to-roll' coating methods. However, issues related to power efficiency (PE) are highly hampering the progress of s-OLEDs towards real applications. Herein, we will demonstrate current development of s-OLEDs targeting for high PE with emphasis on introducing (i) theoretical and practical significance in simultaneously achieving close-to-unity (∼100 %) exciton emission and low driving voltage realized by advanced interface modification, bipolar-transporting-type host, all-exciton-harvesting emissive material and customized device architectures to integrate their functions, (ii) novel low-driving-voltage techniques for phosphorescent and thermally activated delayed fluorescence (TADF) s-OLEDs, i.e. barrier-free exciplex host or bipolar co-host scaffold, and charge-trapping- or charge-scattering-free emissive layer (EML) structures by matching the frontier molecular orbitals (FMOs) between host and dopant emitters, (iii) a variety of tactics to effectively alleviate the efficiency roll-off issue at the practically high luminance value, e.g. removing or largely restraining exciton-quenching in the EML and/or interfaces, the utilization of novel emitters with fast radiative decay rate and/or the EML architectures with prompt and efficient Förster energy transfer process. [ABSTRACT FROM AUTHOR]

Efficient blue polymer light-emitting diodes (PLEDs) have been fabricated with a neutral alcohol-soluble polyfluorene, i.e., poly(9,9-bis(6′-diethoxylphosphorylhexyl)fluorene) (PF-EP), as the emitting layer, high work-function Al as the cathode, and poly(vinyl carbazole) as the hole-transporting layer. The PLEDs display a maximum luminous efficiency of 4.0 cd/A and the luminous efficiency >2.4 cd/A in a wide range of current densities. It is found that the promising performance of the devices is attributed to the fact that the PF-EP is not only an efficient blue light-emitting polymer, but it also can facilitate efficient electron injection at the Al/PF-EP interface. [ABSTRACT FROM AUTHOR]

The efficient white polymeric light-emitting diodes based on a white emissive polymer doped with a red phosphorescent dopant were fabricated by spin-coating method. The emission spectrum of the device is broadened to cover the full visible region by doping the red phosphorescent dye and thereby realizes white emission with high color-rendering index (CRI). By controlling the contents of the doped electron-transporting 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole and the red phosphorescent dopant, a luminous efficiency as high as 5.3 cd/A and a power efficiency of 3 lm/W were obtained with a CRI of 92. [ABSTRACT FROM AUTHOR]

The optical waveguide effect limits strongly the light out-coupling efficiency in organic light-emitting diodes (OLEDs). Patterning the transparent ITO anode on the substrate is a potential way to weaken the optical waveguide effect and enhance the light-emitting efficiency of OLEDs. Herein, the one-dimensional (1D) and two-dimensional (2D) periodic patterned ITO/glass substrates have been successfully fabricated by using the holographic lithography technology and used to fabricate highly efficient OLEDs. The periodic micro-structured ITO layer could manipulate the total internal reflection at the organic/ITO interfaces and enhance the scattering effect so as to improve the light out-coupling efficiency. The effect of different micro-structured ITO layers on the light-emitting efficiency was investigated in a kind of orange phosphorescent OLEDs based on the m-MTDATA:Ir(Flpy-CF 3) 3 /TmPyPB emissive layer. The orange OLEDs employing the 1D grating and 2D lattice patterned ITO/glass substrates show the external quantum efficiencies (EQEs) of 25.12% and 29.61%, respectively. The orange OLEDs fabricated with the 2D hole patterned ITO glass substrate demonstrate the best light-emitting performance with a current efficiency of 100.55 cd A−1, an EQE of 31.39% and a power efficiency of 121.50 lm W−1, respectively. The 1D grating and 2D patterned ITO microstructures have been successfully fabricated with the holographic lithography. The phosphorescent OLEDs employing the periodic patterned ITO/glass substrate improve the light out-coupling leading to signigicantly increased light-emitting efficiency. A power efficiency of 121.50 lm W−1 is achieved for yellow phosphorescent OLEDs employing the 2D hole-patterned ITO/glass substrate. Image 1 • The 1D and 2D patterned ITO/glass substrate via holographic lithography enhances the outcoupling of emitted light from the device structure. • The light-emitting efficiencies are greatly increased by using the patterned ITO/glass substrate. • A power efficiency of 121.50 lm W−1 and an external quantum efficiency of 31.39% are achieved for yellow phosphorescent OLEDs employing the 2D hole-patterned ITO/glass substrate. [ABSTRACT FROM AUTHOR]

The morphology with the interpenetrating network and optimized vertical phase separation plays a key role in determining the charge transport and collection in polymer:nonfullerene small molecular acceptors (SMAs) solar cells. However, the crystallization of polymer and SMAs usually occurs simultaneously during film‐forming, thus interfering with the crystallization process of each other, leading to amorphous film with undesirable lateral and vertical phase separation. The poly(3‐hexylthiophene) (P3HT):O‐IDTBR blend is selected as a model system, and controlling film‐forming kinetics to solve these problems is proposed. Herein, a cosolvent 1,2,4‐triclorobenzene (TCB) with selective solubility and a high boiling point is added to the solution, leading to prior crystallization of P3HT and extended film‐forming duration. As a result, the crystallinity of both components is enhanced significantly. Meanwhile, the prior crystallization of P3HT induces solid–liquid phase separation, hence rationalizing the formation of the nano‐interpenetrating network. Moreover, the surface energy drives O‐IDTBR to enrich near the cathode and P3HT to migrate to the anode. Consequently, a highly crystalline nano‐interpenetrating network with proper vertical phase separation is obtained. The optimal morphology improves charge transport and suppresses bimolecular recombination, boosting the power conversion efficiency from 4.45% to 7.18%, which is the highest performance in P3HT‐based binary nonfullerene solar cells. [ABSTRACT FROM AUTHOR]

To realize power efficient solution-processed phosphorescent organic light-emitting diodes (s-PhOLEDs), the corresponding high driving voltage issue should be well solved. To solve it, efforts have been devoted to the exploitation of novel host or interfacial materials. However, the issues of charge trapping of phosphor and/or charge injection barrier are still serious, largely restraining the power efficiency (PE) levels. Herein, with the utilization of an exciplex-forming couple 4, 4′, 4″ -tris[3-methylphenyl(phenyl)amino]triphenylamine (m-MTDATA) and 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (TmPyPB), the efficient charge injection and transporting, barrier-free hole-electron recombination for the formation of the interfacial exciplex, and elimination of charge traps of phosphors in the emissive layer are realized simultaneously, resulting in a turn-on voltage of 2.36 V, a record high PE of 97.2 lm W−1, as well as extremely low driving voltage of 2.60 V at 100 cd m−2, 3.03 V at 1000 cd m−2 and 4.08 V at 10000 cd m−2. This report is the first time that the PE performance of s-PhOLED approaches 100 lm W−1 high level, even superior to the corresponding state-of-the-art performance of the same color vacuum-deposited PhOLED (v-PhOLED) counterpart. We anticipate this report opens a new avenue for achieving power efficient monochromatic and white s-PhOLEDs with simple structures. [ABSTRACT FROM AUTHOR]

The back cover page of the journal "Angewandte Chemie International Edition" is presented.

The cover page of the journal "Angewandte Chemie" is presented.