A Diboron-Based Thermally Activated Delayed Fluorescent Material for Versatile Applications of Organic Light-Emitting Diodes

Abstract

Thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) have attracted public attention due to their high external quantum efficiency (EQE) and implication in future display technology. Despite their improved efficiency, TADFbased OLEDs still suffer from serious efficiency roll-off and short operational lifetimes. Herein, a diboron-based molecule, PhCzDBA, is designed and its device exhibits a maximum EQE (EQE max ) of 33.8% and only slight roll-off (EQE max of 31.5% at 1000 cd m −2 and 28.8% at 3000 cd m −2 ). Furthermore, it shows superior stability among reported TADF devices (LT 80 of 113 h at the initial luminance of 3000 cd m −2 ). Remarkably, its nondoped OLED shows a high EQE max of 17.7% with a λ max > 580 nm, surpassing most orange nondoped OLEDs. Moreover, a decent white OLED device with an EQE max of 16.4% and a color rendering index (CRI) of 73 can be achieved by incorporating a simple sandwich emitting layer configuration, exhibiting the potential and diverse applications in many aspects.

Thermally Activated Delayed Fluorescent Emitters Based on Cyanobenzene Exhibiting Fast Reverse Intersystem Crossing to Suppress the Efficiency Roll-Off

“…In the last two decades, organic light-emitting diodes (OLEDs) have attracted great attentions owing to the use of the triplet excited-available emitters. − As one promising type of these emitters, thermally activated delayed fluorescent (TADF) emitters are capable of pushing 75% triplet excitons to emit via the reverse intersystem crossing (RISC) process, and theoretically the 100% internal quantum efficiency (IQE) can be achieved. − However, the ultralong delayed lifetime usually leads to the serious fluorescence quenching in aggregate states. As a result, the luminescent efficiency is sharply compromised in OLEDs under high current density, which is called efficiency roll-off. , …”

“…As a result, the luminescent efficiency is sharply compromised in OLEDs under high current density, which is called efficiency roll-off. 9,10 To address the above challenge, many approaches, such as selecting suitable functional layers in a device and modifying the molecular structures of emitters, have been reported. Among all these methods, from the perspective of the device, doping the TADF emitters in an appropriate hosts is one of the most effective method to reduce triplet exciton density.…”

High-performance near-infrared OLEDs maximized at 925 nm and 1022 nm through interfacial energy transfer

“…Thus, it is essential to improve the device structure and materials to increase the outcoupling efficiency. Some recent studies have shown that QD-LEDs and PeLEDs can achieve an EQE above 25% without using any out-coupling enhancement method [20][21][22][23][24][25] .…”

Full-color-emitting fluids from carbon dots stabilized in nonconventionally fluorescent micelles

“…Photoluminescent (PL) materials have wide applications in bioimaging, light-emitting diodes, anti-counterfeiting and sensing. 1,2 Persistent exploration towards this direction has led to the emergence of encouraging new materials, among which carbon dots (CDs) have received increasing attention due to their ease of preparation and tunable luminescence. 3 Compared to traditional chromophores, CDs lack a defined molecular structure, which leads to a more complicated PL mechanism.…”