High Triplet Energy Phosphine Sulfide Host Materials with Selectively Modulated Electrical Performance for Blue Electrophosphorescence

Abstract

Bipolar host materials consisting of electron-donating (D) and -accepting (A) moieties are significant advances in broadening the recombination zone to suppress the quenching effects of emissive phosphors in the emission layer for achieving a high-efficiency blue electrophosphorescence device. However, it is still a daunting and challenging issue to design bipolar blue host molecules that have high triplet energy (E T ) and balanced charge transportation simultaneously in the directly linked D−A molecules, owing to their high tendency in forming low-energy charge-transfer (CT) states. Herein, on account of the high-polarization, electron-withdrawing, and insulating features of the acceptor of aryl phosphine sulfide (APS), a series of blue host materials in D−A/D−A−D skeletons with high E T 's are constructed and facilely prepared. Thus, designed host materials show high E T 's up to 3.02 eV, suitable highest occupied molecular orbitals and lowest unoccupied molecular orbitals, and balanced hole/electron flux, which facilitate blue phosphorescent organic light-emitting diodes (PhOLEDs) with a maximum external quantum efficiency of 14.1%, power efficiency of 21.4 lm W −1 , and current efficiency of 27.8 cd A −1 . These findings demonstrate the important role of APS unit in designing and developing host materials with high E T 's and balanced carrier flux for high-performance blue PhOLEDs.

Access to Phosphine-Containing Quinazolinones Enabled by Photo-Induced Radical Phosphorylation/Cyclization of Unactivated Alkenes

“…Organophosphorus compounds are not only essential for biological systems but also of great value in modern organic synthesis, medicinal chemistry, and materials sciences . In particular, heterocycle-containing organophosphorus compounds are ubiquitous in drugs and active molecules .…”

Peripheral carbazole or cyano substitutents in poly (aryl ether) based bipolar polymeric hosts: Increase the hole or electron injection properties for blue phosphorescent polymer light emitting diodes

“…A series of active charge transporting groups were investigated， including various hole transport units (carbazole, 17,18 triphenylamine, 19 dibenzofuran, 20 dimethyl‐9,10‐dihydroacridine, 21 etc.) and electron transport moieties (phosphine oxide, 22 phosphine sulfide, 20 oxadiazole, 23 and triazine, 24 pyridine 21 etc.). Regarding high E T , excellent electron and hole transporting ability, good thermal and morphological stability, a phosphine oxide, and carbazole group are being used respectively to fulfill the problems 25,26 .…”

“…In light of this, an effective strategy of introducing a donor or acceptor active group into bipolar host molecules, have been demonstrated to obtain the objective materials, which could not only endow hosts with high enough E T but also give it a better carrier injection and transport ability. A series of active charge transporting groups were investigated， including various hole transport units (carbazole, 17,18 triphenylamine, 19 dibenzofuran, 20 dimethyl‐9,10‐dihydroacridine, 21 etc.) and electron transport moieties (phosphine oxide, 22 phosphine sulfide, 20 oxadiazole, 23 and triazine, 24 pyridine 21 etc.).…”

“…Regarding high E T , excellent electron and hole transporting ability, good thermal and morphological stability, a phosphine oxide, and carbazole group are being used respectively to fulfill the problems 25,26 . On the base of above points, some small molecular hosts successfully used in blue PhOLEDs have been reported, such as dibenzo[b,d]‐thiophen‐2‐yldiphenylphosphine sulfide (DBTSPS), 20 9,9‐dimethyl‐10‐(2‐methyl‐3',5'‐di(pyridin‐3‐yl)‐[1,1'‐biphenyl]‐4‐yl)‐9,10‐dihydroacridine (DPMBP‐DMAC) 21 …”

Rational Design of Bipolar Host and Thermally Activated Delayed Fluorescence Materials in Donor–Acceptor Molecular Architecture: A Theoretical Study

“…5 The precise optical, electrical, photophysical, electrochemical, and luminescent properties of D−A materials can be rationally controlled by constructing the appropriate electron-rich donor (D) and electron-deficient acceptor (A) units, 6 changing their chemical connections, and adjusting the space and molecular geometry in the D−A structures. 7 A large variety of organic semiconductors have been designed in D−A architectures, ranging from fluorescent/phosphorescent emitters, 8 host molecules, 9 thermally activated delayed fluorescence (TADF) materials, 10 stable radicals, 11 photovoltaic polymers, 3 to exciplexes. 12 Nevertheless, the extremely high diversity and flexibility of D−A structures are hard to harness, and totally different organic optoelectronic materials would result, which significantly limits the design and development of advanced optoelectronic D−A molecules.…”