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The rapid development of nanotechnology for the last 30 years has enabled a rapid expansion in the applications of functional nanoparticles (NPs) on optoelectronic devices. Especially, NPs are of high significance in organic light‐emitting diodes (OLEDs) as they provide feasible solutions to the enduring challenges related to higher device efficiency. The use of NPs with designed structure and functionality is demonstrated, indicative of their great application potentials in OLEDs. Herein, the recent advances in OLEDs with the utilization of functional NPs are summarized. Starting with a brief overview about the unique properties of NPs, comprehensive roles of NPs in OLEDs, which include improving carrier injection abilities, local surface plasmonic resonance, light scattering, and magnetic field effects, are discussed together with their latest research progresses. Furthermore, one‐component and multicomponent heterostructured NPs with multifunctional capabilities in OLEDs are overviewed. Following the summarization of the roles of NPs in OLEDs and their latest research progress, a brief conclusion and outlook regarding the future research directions of highly efficient OLEDs by incorporation of NPs are provided. [ABSTRACT FROM AUTHOR]

Fe3O4 has been demonstrated to be an efficient p-dopant in improving the performance of organic light-emitting devices. This paper investigates in detail the role of Fe3O4 in improving the hole injection and the hole transport by the ultraviolet/visible/near-infrared absorption, x-ray, and ultraviolet photoelectron spectroscopy. The results demonstrated that Fe3O4 as a p-dopant has different effectiveness when it is doped into different host materials. The improved properties of the OLEDs with the p-doped N, N'-diphenyl-N,N'-bis (1,1'-biphenyl)-4,4'-diamine layer is mainly due to the enhanced hole injection through the lowering of the hole injection barrier, while the enhanced hole transport plays a more important role for the OLEDs with the p-doped 4,4',4”-tris (3-methylphenylphenylamino) triphenylamine due to their higher ability in the formation of charge transfer complex. [ABSTRACT FROM PUBLISHER]

We propose a plasmonic ultrathin metal grid electrode as a promising light outcoupling strategy in a flexible organic light-emitting device (OLED). The plasmonic ultrathin metal grid electrode consists of an ultrathin Au grid film incorporating with plasmonic subwavelength corrugations, which was fabricated by lithography and nanoimprint technologies, demonstrates excellent optical and electrical properties as the substitute of ITO transparent electrode in flexible OLED. The transmittance of the plasmonic ultrathin Au grid electrode is 88.5% at 550 nm and the sheet resistance is about 36 Ω/sq. The periodic subwavelength corrugations of the plasmonic ultrathin Au grid electrode excite the surface plasmon-polariton (SPP) resonance which is an adverse optical mode with power loss in OLED, and the photons trapped in SPP mode are effectively outcoupled and extracted by the plasmonic corrugations. Compared to the ITO-based device, OLED based on plasmonic ultrathin Au grid electrode realizes a desirable enhancement of 60.3% in current efficiency. In addition, the flexible OLED based on the proposed electrode also exhibits decent mechanical robustness and flexibility with stable electroluminescence performances. Image 1 • A plasmonic ultrathin metal grid film incorporating with corrugations is reported. • The proposed electrode serves as a light extraction strategy in flexible OLED. • A 60.3% enhancement in current efficiency has been achieved. [ABSTRACT FROM AUTHOR]

Instability and large wire-wire contact resistance of silver nanowires (AgNWs) have seriously hindered their practical applications as electrodes in optoelectronic devices. Although various methods have been demonstrated to improve the stability and conductivity of the AgNWs, a simple and low-cost process, especially compatible to the flexible substrates for their applications in flexible devices, is still a challenge. Here, perfluorinated sulfonic acid (PFSA) polymer has been employed as a surface-passivation layer on the AgNWs through a simple surface coating. The PFSA passivation can simultaneously improve the conductivity, thermal stability and mechanical stability of the AgNWs. As a result, the PFSA-passivated AgNWs film maintains an almost constant conductivity under ambient condition after heating for 30 min at 250 °C or 10 days storage at room temperature, and 600 continuous bending cycles at a bending radius of 1 mm. The PFSA-passivated AgNWs have been applied to flexibly organic light emitting devices as their electrodes, and both mechanical stability and long-term operational stability have been improved. Image 1 • Simultaneous improvement of conductivity, stability and flexibility. • Excellent thermal and chemical durability. • Suitable for fabricating flexible OLEDs. [ABSTRACT FROM AUTHOR]