Recent Advances in Triplet–Triplet Annihilation-Based Materials and Their Applications in Electroluminescence

Abstract

Efficient and stable blue organic light-emitting devices (OLEDs) represent one of the most important components in future solid-state lighting and full color displays. Although red and green OLEDs have been successfully commercialized, it remains challenging to realize blue OLEDs showing high efficiency and high stability simultaneously, restricting their commercialization. Triplet−triplet annihilation (TTA)-based materials have been emerging as a new category of electroluminescent or host materials with promising potential for highly efficient and stable blue devices due to their appealing photophysical properties (e.g., ability to generate emissive singlet excited states through TTA process, high photoluminescence quantum yield, ease of molecular design, etc.). Recently, research on TTA-based materials toward high-performance blue OLEDs has received an increasing attention. In this review, recent research advances on the molecular design strategies, photophysical properties of TTA-based materials (both blue emitters and host materials), mechanism of TTA-based electroluminescence, as well as their OLED applications are presented comprehensively. Moreover, potential perspectives with future research opportunities in this field are also described. We believe that the emerging TTA-based materials will bring more opportunities for developing a large family of novel photofunctional materials showing appealing and tunable photophysical properties, thus providing new opportunities for high-efficiency and stable blue electroluminescence in the future.

Organoboron-based multiple-resonance emitters: synthesis, structure–property correlations, and prospects

“…As a result, DABNA derivatives are now widely commercialised as blue emitters in triplet–triplet annihilation (TTA)-driven fluorescent devices for smartphones and televisions. 87–91 However, MR emitters have not been implemented as TADF emitters because of their rapid degradation through the long-lived T 1 state in TADF-OLEDs. 87 One of the most effective ways of realising reliable TADF devices is boosting the RISC of MR emitters.…”

Acceptor–donor–acceptor based thermally activated delayed fluorescent materials: structure–property insights and electroluminescence performances

“…Later on, to extend the TADF materials, several types were developed enormously, such as D-p-A, 43 D-A-D, 44 and D-A-A, 45 respectively. 46 Among the developed TADF materials, some of the most commonly used acceptors are triazine, pyridine, pyrimidine, and naphthalimide, and donors are carbazole, acridine, phenoxazine, phenothiazine, indolocarbazole, and spiro based donors. 47 On the other hand, boron-based acceptor inserted materials were also developed mainly for blue OLEDs.…”

Reducing intersystem crossing rates of boron emitters for high-efficiency and long-lifetime deep-blue OLEDs

“…[38][39][40][41][42][43][44][45][46][47][48][49][50] While the research studies on boron emitters have mainly focused on the promotion of device efficiency through the TADF characteristics, the development of boron-based emitters for F-OLEDs is extremely scare. [51][52][53][54] Currently, it remains unclear what kind of organic blue emitters can simultaneously achieve high efficiency, high color purity and long operational lifetime in F-OLEDs. Herein, we successfully design and synthesize three types of boron-based emitters with asymmetrical structures (B-N-S-1/2/3) by integrating a tetrahydroquinoline (THQN) type donor and another pairing donor (Scheme 1).…”