We demonstrate enhanced light out-coupling efficiency of organic light-emitting diodes by applying a multilayer stacked electrode structure consisting of fast and cost-effective sol-gel processed tantalum pentoxide (TaO), thin layer of Au and molybdenum trioxide (MoO). The application of the TaO/Au/MoO electrode can modulate the optical characteristics of the device due to the optical microcavity effect. The refractive index of the sol-gel processed TaO thin film varied depending on the annealing temperature and reached a maximum at 400 °C (n = 2.2 at 512 nm). The influence of the refractive index of the TaO layer and the thickness of the multilayer electrode stack on the optical microcavity effect was systematically investigated. The device with the TaO/Au/MoO electrode, fabricated at an optimum condition based on the simulation result by calculating the photon flux, exhibited 52% enhancement in light out-coupling efficiency at 1000 cd/m and improved color stability with the viewing angle, having near-Lambertian emission.
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http://dx.doi.org/10.1364/OE.25.027886 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, 130022, P. R. China.
The multiple resonance thermally activated delayed fluorescence (MR-TADF) device has drawn great attention due to their outstanding efficiency and color purity. However, the efficiency of solution-processed MR-TADF devices is still far behind their vacuum-deposited counterparts, due to the uncontrollable horizontal emitting dipole orientation for emitters during solution process, resulting in low light out-coupling efficiency. Here, we proposed a new strategy namely electrostatic interaction between a dendritic host with high positive electrostatic potential (ESP) and dendritic emitter with multiple negative ESP sites, which could induce high horizontal dipole ratio (Θ) up to 83.
View Article and Find Full Text PDFMater Horiz
December 2024
Macao Institute of Materials Science and Engineering (MIMSE), MUST-SUDA Joint Research Center for Advanced Functional Materials, Zhuhai MUST Science and Technology Research Institute, Macau University of Science and Technology, Taipa 999078, Macau, China.
Capping layers (CPLs) are commonly employed in top-emitting organic light-emitting diodes (TEOLEDs) due to their ability to optimize color purity, enhance external light out-coupling efficiency, and improve device stability. However, the mismatch in refractive index between CPLs and thin film encapsulation (TFE) often induces light trapping. This study introduces a novel approach by combining a low refractive index material, lithium fluoride (LiF), with the traditional TFE material, silicon nitride (SiN), to form a combined CPL (LiF/SiN), resulting in improved light outcoupling and light reflection properties.
View Article and Find Full Text PDFAdv Mater
December 2024
Experimental Center of Advanced Materials, School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, 100081, China.
Anisotropic nanoplatelets (NPLs) possess strong in-plane transition dipole moments and out-of-plane emission, which enable a maximum photon out-coupling efficiency of 40% and a high gain coefficient, making them ideal candidates for light-emitting diodes (LEDs) and lasers. However, the unbalanced surface energy between the side and top facets of NPLs results in poor thermal stability and high susceptibility to ripening at elevated temperatures, which complicates the growth of the shell. To address this issue, a gradient crown (CdSeS) around the CdSe NPLs is designed to stabilize the high energy side facets.
View Article and Find Full Text PDFNat Commun
November 2024
Institute of Materials Science of Barcelona ICMAB-CSIC, Campus UAB, Bellaterra, Spain.
Direct manipulation of light spin-angular momentum is desired in optoelectronic applications such as, displays, telecommunications, or imaging. Generating polarized light from luminophores avoids using optical components that cause brightness losses and hamper on-chip integration of light sources. Endowing chirality to achiral emitters for direct generation of polarized light benefits from existing materials and can be achieved by chiral nanophotonics.
View Article and Find Full Text PDFMaterials (Basel)
November 2024
Department of Semiconductor Science and Technology, Jeonbuk National University, Jeonju 54896, Republic of Korea.
We investigated hybrid functional transparent conductive electrodes (HFTCEs) composed of indium-tin-oxide (ITO) and silver nanowires (AgNWs) for the enhancement of output efficiency in GaN-based ultraviolet light-emitting diodes (UVLEDs). The HFTCEs demonstrated an optical transmittance of 69.5% at a wavelength of 380 nm and a sheet resistance of 16.
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