Resonance hosts for high efficiency solution-processed blue and white electrophosphorescent devices

Phosphine Sulfide-Based Bipolar Host Materials for Blue Phosphorescent Organic Light-Emitting Diodes

“…Density-functional theory (DFT) calculations were further performed to acquire insight into the structure–property relationships of CzPhPS , DCzPhPS , and TCzPhPS [ 30 ] . As shown in Figure 4 , the LUMO of these three compounds is predominantly located on the triphenylphosphine sulfide group due to its electron-withdrawing feature, while the HOMO is mainly distributed on electron-donating carbazole units, as expected.…”

AIE-active organic resonance molecules for highly sensitive dynamic explosive detection

“…14 A series of organic resonance molecules containing N-PQX (X = O, S, or Se) or N-CQO resonance structures were developed based on donor-resonance-acceptor or donor-resonance-donor architectures. [14][15][16][17][18] Owing to the facile resonance variation in realizing the dynamically balanced charge transport, the external quantum efficiencies (EQEs) of the blue and white phosphorescent OLEDs employing these resonance molecules as host materials show high values of up to 31.2% 18 and 23.5%, 19 respectively; the EQEs of the blue and green thermally activated delayed fluorescence OLEDs reach 20.5% 18 and 15%, respectively. 14 Furthermore, the intersystem crossing (ISC) process from the excited singlet to triplet states can be significantly promoted by virtue of the varied excited-state energies of resonance canonical forms for reducing the real-time splitting energy between the lowest singlet and triplet states, resulting in simultaneously elongated organic afterglow lifetime and improved efficiency.…”

Achieving Balanced Electrical Performance of Host Material through Dual N–P═O Resonance Linkage for Efficient Electroluminescence

“…Excitingly, organic semiconductors having resonance linkages are capable of showing dynamically variable tautomerization between neutral and charged resonance forms for charge redistribution (Figure a), thus leading to the selective evoking of optimal electrical properties without any adverse influence on the optical attributes and providing a new way for search and design of optoelectronic materials with purposefully regulated properties. − Also, it has been manifested that the resonance molecules with more enantiotropic resonances (Figure a, bottom) demonstrate enhanced dynamic adaption ability to achieve boosted electronic properties compared to those with less enantiotropic resonance (Figure a, top) due to their more dynamic canonical form to improve the possibility for the presence of these charged forms to enable the construction of the dynamic carrier transporting channels. Experimentally, the maximum external quantum efficiency (EQE) of blue phosphorescent devices was 16.5% using typical D–r–A-type hosts with enantiotropic N + P–O – resonances; and through resonance engineering, a D–r–A-type host with enantiotropic N + P–S – resonances was developed and the EQE of its blue PhOLED could be increased to 21.3%. , These results indicated that through rational resonance linkage and engineering, the eventual device performance hosted by resonance molecules can be efficiently improved. Despite these successes, due to the limitation of the resonance linkages, the molecular structure of resonance molecules could not be diversified.…”