Molecular Design Strategy of Organic Thermally Activated Delayed Fluorescence Emitters

TLDR

TADF emitters are promising for high‑efficiency OLEDs because they can theoretically reach 100 % internal quantum efficiency, and since their first demonstration of nearly 20 % external quantum efficiency, many variants have been developed. This study reviews molecular design strategies for organic TADF emitters, classifying them by required material parameters, and proposes future directions to make them competitive with phosphorescent emitters. The authors classify TADF emitters into several categories based on the material parameters required for efficient delayed fluorescence. Recent TADF emitters have achieved external quantum efficiencies of ~37 % in blue, >30 % in green, and ~18 % in red devices, indicating that TADF OLEDs could replace high‑efficiency phosphorescent OLEDs.

Abstract

Recently, organic thermally activated delayed fluorescence (TADF) emitters have attracted a great deal of attention because they can theoretically realize 100% internal quantum efficiency. Many TADF emitters have been developed since the first demonstration of close to 20% external quantum efficiency in the devices. Recently developed TADF emitters demonstrated close to 37% external quantum efficiency in blue, above 30% external quantum efficiency in green, and close to 18% external quantum efficiency in red devices. Therefore, TADF organic light-emitting diodes could potentially be substituted for high-efficiency phosphorescent organic light-emitting diodes. In this work, we reviewed molecular design strategies of organic-based TADF emitters by classifying them into several categories depending on the material parameters required for the TADF emitters. In addition, we proposed a future development direction of TADF emitters to make them competitive with phosphorescent emitters.