Triarylamine-Pyridine-Carbonitriles for Organic Light-Emitting Devices with EQE Nearly 40%

Abstract

Highly efficient thermally activated delayed fluorescence (TADF) molecules are in urgent demand for solid-state lighting and full-color displays. Here, the design and synthesis of three triarylamine-pyridine-carbonitrile-based TADF compounds, TPAPPC, TPAmPPC, and tTPAmPPC, are shown. They exhibit excellent photoluminescence quantum yields of 79-100% with small Delta E-ST values, fast reverse intersystem crossing (RISC), and high horizontal dipole ratios (Theta(//) = 86-88%) in the thin films leading to the enhancement of device light outcoupling. Consequently, a green organic light-emitting diode (OLED) based on TPAmPPC shows a high average external quantum efficiency of 38.8 +/- 0.6%, a current efficiency of 130.1 +/- 2.1 cd A(-1), and a power efficiency of 136.3 +/- 2.2 lm W-1. The highest device efficiency of 39.8% appears to be record-breaking among TADF-based OLEDs to date. In addition, the TPAmPPC-based device shows superior operation lifetime and high-temperature resistance. It is worth noting that the TPA-PPC-based materials have excellent optical properties and the potential for making them strong candidates for TADF practical application.