Poor wide field-of-view (FOV) performances and low production yields are major factors that restrict the application of organic light-emitting diodes (OLEDs) in large-size panels. In this paper, we propose an optimization and analysis method to improve optical performances of stratified OLEDs over wide FOV with consideration of the thickness tolerance in the practical production process. With key optical performance parameters defined using the angle-dependent luminescence spectra, including the external quantum efficiency (EQE), current efficiency (CE), just noticeable color difference (JNCD), and the color coordinates, the optimization of OLEDs over wide FOV is described as a multi-parameter and multi-objective optimization problem which is accomplished by the genetic algorithms (GAs). Further, the thickness tolerance is introduced to improve the structure stability considering thickness fluctuations in the practical production process. Appropriate thickness tolerances can be determined to achieve stable structures for the OLED device by defining and analyzing the distributions of preference regions of the GA output noninferior solutions and the correlation coefficients between the layer thicknesses. Based on the proposed methods, high-throughput simulations are carried out on a typical Green Bottom-emitting OLED (G-BOLED) to design a stable device structure with high-performances. Experimental results demonstrate that compared with the initial device, the performances of the optimized device have been significantly improved, with the CE improved by over 30% in the normal direction, the EQE improved by over 20%, and the JNCD reduced from 4.45 to 1.36 over the whole FOV of 0-60°. In addition, within the thickness fluctuation in the practical process, optimized devices can strictly satisfy the "Best" preferred region, indicating that the structure is more stable against thickness fluctuations in the practical production process. The proposed optimization method can simultaneously improve optical performances over wide FOV and provide a stable structure for stratified OLEDs, and it therefore can be expected to improve the production yields and promote the OLEDs applied to large-size panels.
Objective. To study and track the reliability growth of manned spaceflight cabin-borne equipment in the course of its development. Method. A new technique of reliability growth estimation and prediction, which is composed of the Crow model and test data conversion (TDC) method was used. Result. The estimation and prediction value of the reliability growth conformed to its expectations. Conclusion. The method could dynamically estimate and predict the reliability of the equipment by making full use of various test information in the course of its development. It offered not only a possibility of tracking the equipment reliability growth, but also the reference for quality control in manned spaceflight cabin-borne equipment design and development process.
The dipole orientation and distribution have significant influence on the performances of OLEDs, and they are prerequisites for the optical design and analysis of OLEDs. In this paper, based on the dipole radiation model for OLEDs, a two‐step inversion method is proposed to accurately achieve dipole features simultaneously, including dipole orientation and distribution, in OLED devices, without knowing the approximate shape of the dipole distribution.
Colloidal quantum dot (QD) display is expected to be a promising technology for the next generation display due to the advantages of QDs. In this work, we fabricated 6.6 inch QD display panel by inkjet printing technology, being cooperated with active matrix organic light emitting diodes (AMOLEDs). Here 3‐stack blue OLEDs (BOLEDs) with top‐emission structure acted as backlight and red QD layer acted as converted materials, which exhibited high quantum efficiency, high luminance, high color purity and improved wide viewing angle of output emission. We believe that inkjet‐printed QD display with AMOLEDs would be promising candidate for the next generation display and lighting in the near future.
Thermally activated delayed fluorescence (TADF) materials have opened a new chapter for high-efficiency and low-cost organic light-emitting diodes (OLEDs). Herein, we describe a novel and effective design strategy for TADF emitters which includes introducing a carbazole donor unit at the ortho-position, at which the donor and acceptor groups are spatially in close proximity to guarantee the existence of intramolecular electrostatic attraction and through-space charge transfer, leading to reduced structural vibrations, suppressed non-radiative decay and rapid radiative decay to avoid excited state energy loss. As a result, a green TADF emitter (2Cz-DPS) showing high solid-state photoluminescence quantum efficiency (91.9%) and excellent OLED performance was produced. Theoretical simulations reveal that the non-adiabatic coupling accelerates the reverse intersystem crossing of 2Cz-DPS, resulting in a state-of-the-art non-doped OLED with an extremely high external quantum efficiency of 28.7%.
Three new linear benzene-fused bis(tetrathiafulvalene) compounds (4–6) were synthesized and characterized. Compounds 4 and 5, comprising branched alkyl chains (2-ethylbutyl and 2-ethylhexyl, respectively), had very good solubility in common organic solvents and were successfully used as p-channel semiconductors in solution-processed organic field-effect transistors (FET). The FET device based on 5 showed a mobility of 5.6 × 10–4 cm2 V–1 s–1 with an on/off ratio of 1.6 × 104, and the devices based on 4 and 5 displayed good reproducibility in air. In addition, 6, bearing the long n-dodecyl chains, exhibited self-assembly behavior; one-dimensional self-assembly micron-scale ribbons formed in solution and were revealed by scanning electron microscopy on SiO2 substrates.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
All organic layers inkjet printed OLEDs have been successfully developed with a printable electronic transport layer (ETL). A jettable ETL ink was prepared with a commercially soluble electronic transport material and alcohol solvents. Based on orthogonal solvent systems, the deposition of ETL caused little damage to the emission under‐layer. And ETL printed OLEDs show comparable performance with its evaporation ETL counterparts.
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