Host Engineering of Deep‐Blue‐Fluorescent Organic Light‐Emitting Diodes with High Operational Stability and Narrowband Emission

Abstract: Abstract Blue organic light‐emitting diodes (OLEDs) are essential components in optoelectronic devices, providing high‐energy emissions for vibrant displays and white light illumination. However, their widespread application is hindered by high operating voltages and limited operational lifetimes. Upconversion (UC)‐OLEDs, which utilize the triplet–triplet annihilation (TTA) UC process to emit light, offer blue light emission with an ultra‐low turn‐on voltage of 1.5 V, thereby reducing energy loss and enhancing device longevity. Despite these advantages, the strategy for selecting dopant—key determinants of emission color in UC‐OLED—remains unclear, leading to the emission of impure sky‐blue light in a previous report. This study investigates the effect of dopants on UC‐OLED performance by examining how molecular structure and properties affect charge transport through the formation of deep traps, thereby elucidating dopant selection rules. By developing optimized dopants, a UC‐OLED capable of emitting narrowband deep‐blue light at 447 nm with a full width at half maximum (FWHM) of 20 nm, driven by a 1.5 V battery, is demonstrated.

TL;DR: Researchers investigated the mechanism behind polyimide's friction-greening phenomenon, finding that increasing process temperature regularizes PI's chain structure, enhancing conductivity and reducing charge accumulation, thereby mitigating TFT threshold voltage drift.

TL;DR: Five practical examples involving a wide variety of systems and analysis methods are given to illustrate the usefulness of Multiwfn, a multifunctional program for wavefunction analysis.

Abstract: Multiwfn is a multifunctional program for wavefunction analysis. Its main functions are: (1) Calculating and visualizing real space function, such as electrostatic potential and electron localization function at point, in a line, in a plane or in a spatial scope. (2) Population analysis. (3) Bond order analysis. (4) Orbital composition analysis. (5) Plot density‐of‐states and spectrum. (6) Topology analysis for electron density. Some other useful utilities involved in quantum chemistry studies are also provided. The built‐in graph module enables the results of wavefunction analysis to be plotted directly or exported to high‐quality graphic file. The program interface is very user‐friendly and suitable for both research and teaching purpose. The code of Multiwfn is substantially optimized and parallelized. Its efficiency is demonstrated to be significantly higher than related programs with the same functions. Five practical examples involving a wide variety of systems and analysis methods are given to illustrate the usefulness of Multiwfn. The program is free of charge and open‐source. Its precompiled file and source codes are available from http://multiwfn.codeplex.com. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011

TL;DR: In this paper, an analysis of the performances of a parameter free density functional model (PBE0) obtained combining the so-called PBE generalized gradient functional with a predefined amount of exact exchange is presented.

TL;DR: In this paper, a split-valence extended gaussian basis set was used to obtain the LCAO-MO-SCF energies of closed shell species with two non-hydrogen atoms.