Using Guest–Host Interactions To Optimize the Efficiency of TADF OLEDs

Abstract

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Regio- and conformational isomerization critical to design of efficient thermally-activated delayed fluorescence emitters

“…6). It is thus the small energy gap between the 3 LE and CT states (both 1 CT and 3 CT) that gives rise to the thermally-activated nature of the rISC713 and efficient OLED performance14. The second-order vibrational coupling model of rISC (refs 6, 7) enables us to understand the effects of energy ordering, and in this context we show how conformational and regio-isomerism can greatly effect rISC, TADF and ultimately device efficiency.…”

“…The second-order vibrational coupling model of rISC (refs 6, 7) enables us to understand the effects of energy ordering, and in this context we show how conformational and regio-isomerism can greatly effect rISC, TADF and ultimately device efficiency. These structural factors must also be considered in designing the highest efficiency TADF emitters along with energy level ordering13 and host environment within the device14.…”

Thermally Activated Delayed Fluorescence Emitters for Deep Blue Organic Light Emitting Diodes: A Review of Recent Advances

“…The spin-orbit vibronic coupling is also another major important factor in the design of TADF materials. To date, investigations concerning the relationship existing between spin-orbit coupling and RISC are still rare [60][61][62][63]. While aiming at designing deep blue TADF emitters, several parameters should be taken under consideration, such as the π-conjugation length, the redox potential of both the electron-releasing and electron-withdrawing moieties, as well as the degree of conjugation, which is allowed between the two moieties.…”

Two novel blue phosphorescent host materials containing phenothiazine-5,5-dioxide structure derivatives

“…Compared with traditional fluorescence OLEDs which only utilize singlet (25%) excitons for electroluminescence, PhOLEDs can simultaneously harvest both the singlet and triplet (75%) excitons through spin-orbit coupling (SOC), and obtain nearly 100% of the internal quantum efficiency (IQE). Thus, most of researchers have focused on phosphorescent organic light-emitting diodes (PhOLEDs) all over the world [7–8]. With the deepening of this research, the performance of red and green electroluminescent devices has been able to meet the commercial requirements, but the blue electroluminescent devices have several weaknesses such as low efficiency and poor stability and so on, which hinder its development.…”