Novel “Hot Exciton” Blue Fluorophores for High Performance Fluorescent/Phosphorescent Hybrid White Organic Light-Emitting Diodes with Superhigh Phosphorescent Dopant Concentration and Improved Efficiency Roll-Off

Abstract

Two blue fluorophores with excellent hybridized local and charge-transfer (HLCT) and "hot exciton" properties were developed as the blue emitter and the host for orange-red phosphor to achieve highly efficient fluorescent/phosphorescent (F/P) hybrid white organic light-emitting diodes (WOLEDs) in a single-emissive-layer single-dopant (SEML-SD) architecture even at a high concentration of phosphorescent dopant. In the devices, part of the triplet excitons of the blue fluorophores can be utilized to realize reverse intersystem crossing from the triplet excited states to the singlet excited states for blue emission, and the diffusion volume range of the triplet excitons is reduced significantly. When the phosphorescent dopant concentration is up to 1.0 wt %, which is ten times higher than the traditional single-EML-SD F/P hybrid WOLEDs, highly efficient white emission was still achieved with maximum total external quantum efficiency (EQE) of 23.8%, current efficiency (CE) of 56.1 cd A(-1), and power efficiency (PE) of 62.9 lm W(1-). The results will supply a novel method for obtaining high efficiency F/P hybrid WOLEDs in a SEML-SD architecture with easily controllable doping concentration.

Efficient Deep Blue Electroluminescence with an External Quantum Efficiency of 6.8% and CIEy < 0.08 Based on a Phenanthroimidazole–Sulfone Hybrid Donor–Acceptor Molecule

“…42,43 Whereas in most cases it is used as the acceptor part and seldom as donor moiety. 44,45 Herein, phenanthroimidazole is selected as the weak donor and sulfone is used as the moderate acceptor. The D/A moieties are linked by a phenyl π bridge and the corresponding symmetric D-π-A-π-D structure molecule PMSO is constructed.…”

Large-area, uniform white light LED source on a flexible substrate

“…The luminous efficiency of cool white LED (5000K of CCT) is 120 lm/W and CRI is 70 whereas the warm white LED (3000K of CCT) can obtain 80 lm/W and CRI value of 81. Moreover, compared to other studies related to large-area lighting source [19][20][21], the luminous efficiency of the proposed device is compatible and has the potential to use in the flexible lighting application because of high lumen efficiency and low cost. Furthermore, we measure the luminance of the flexible white LED at nine point measurement method and calculate the uniformity with the formula:…”

Efficient fluorescent OLEDS based on assistant acceptor modulated HLCT emissive state for enhancing singlet exciton utilization

“…Efficient deep blue emitters are very important in at-panel displays because of reduced power consumption [1][2][3] and to sensitize the dopants for white light emission, [4][5][6] however, development of blue OLEDs lags behind that of green and red counterparts due to the wider energy gap which leads to unbalanced charge injection/transportation results in poor efficiency. [7][8][9][10][11] Phenanthroimidazole (PI) with pyrrole (N1) and pyridine-like (N3) nitrogen atoms exhibits bipolar characteristics, unmodied PI hinders its application as a potential EL material.…”