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The next generation of optoelectronic devices requires transparent conductive electrodes to be flexible, inexpensive and compatible with large scale manufacturing processes. We report an ultrasmooth, highly conductive and transparent composite electrode on a flexible photopolymer substrate by employing a template stripping method. A random silver nanowire (AgNW) network buried in poly(3,4ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) film constituted the composite electrode. Besides the effectively decreased surface roughness, its sheet resistance and transmittance are comparable to those of conventional PEDOT:PSS electrode. As a result, the efficiency of the OLEDs based on the composite electrode exhibited 25% enhancement compared to the OLEDs with conventional PEDOT:PSS electrode. Moreover, the performance of the flexible OLEDs remains stable after over one hundred bending cycles. [ABSTRACT FROM AUTHOR]

We have demonstrated an indium-tin-oxide free organic light-emitting device (OLED) with improved efficiency by doping poly (3,4-ethylene dioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) with graphene oxide (GO) as a composite anode. In comparison with a pure PEDOT:PSS anode, 55% enhancement in efficiency has been obtained for the OLEDs based on the PEDOT:PSS/GO composite anode at an optimal condition. The PEDOT:PSS/GO composite anode shows a lower hole-injection barrier, which contributes to the improved device efficiency. Moreover, both high transmittance and good surface morphology similar to that of the pure PEDOT:PSS film also contribute to the enhanced efficiency. It is obvious that composite anode will generally be applicable in organic optoelectronic devices which require smooth and transparent anode. [ABSTRACT FROM AUTHOR]

An improved efficiency from an encapsulated flexible top-emitting organic light-emitting device (FTOLED) has been demonstrated by integrating a microstructure onto the polymer encapsulation film. Soft-nanoimprint lithography is employed to integrate the microstructure onto the polymer surface, which enables large area fabrication with high quality, low cost, and repeatable use of the poly(dimethylsiloxane) mold. The light extraction of the FTOLEDs has been improved by integrating the microstructure with two-dimensional tapered micropillars array on the polymer encapsulation film, which can suppress the reflection by enhancing the critical angle of total reflection owing to its gradually changed refractive index. Moreover, the microstructured surface exhibits a hydrophobic property owing to its high contact angle, which results in a self-cleaning ability to protect the FTOLEDs from being polluted by water droplets and dust particles in practical applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] An ITO-free flexible OLED with improved efficiency has been fabricated. [•] Template stripping process has been employed to fabricate the ITO-free OLEDs. [•] The smoothness and conductivity of the PEDOT: PSS anode has been improved. [•] The H2SO4 residues on the PEDOT: PSS anode has been eliminated. [•] The device stability has been improved by eliminating the H2SO4 residues. [ABSTRACT FROM AUTHOR]

Highlights: [•] Viewing-angle independent WTOLEDs have been fabricated. [•] A microcavity with a periodically and gradually changed cavity length has been constructed. [•] The periodic microstructured cavity has been introduced into the WTOLEDs. [•] The viewing-angle independence in both the spectrum and CIE coordinates are obtained. [•] The microstructured WTOLEDs show comparable efficiency to that of the planar TOLEDs. [ABSTRACT FROM AUTHOR]

Abstract: In this work, large-size tetracene- and pentacene-doped 1,4-Bis(4-methylstyryl)-benzene (BSB-Me) crystals were prepared with physical vapor transfer technique. The photoluminescence emission can be adjusted from blue to green and even to red by changing the doping. Their fluorescence features are investigated by both the steady-state fluorescence spectra and time-resolved fluorescence measurements, which indicate highly efficient energy transfer from the host BSB-Me to the acceptor. The PL efficiencies of the tetracene-doped BSB-Me and pentacene-doped BSB-Me crystals are as high as 79% and 47%, the energy transfer efficiency is 49.7% and 73.1%, respectively. Excitation intensity-dependent ultrafast dynamics was further probed, which shows that the kinetics in doped crystals exhibit much less excitation intensity dependence than that of the pure BSB-Me crystals. Our results are relevant to the understanding of ultrafast energy-transfer dynamics in doped crystals and are expected to be of interest for organic light emitting transistors, diodes, and lasers. [Copyright &y& Elsevier]

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]