High performance organic ultraviolet photodetector with efficient electroluminescence realized by a thermally activated delayed fluorescence emitter

Abstract

A high performance organic ultraviolet (UV) photodetector with efficient electroluminescence (EL) was obtained by using a thermally activated delayed fluorescence (TADF) emitter of (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN). An exciton adjusting layer (EAL) was delicately designed to construct an energy-level-aligned heterojunction with 4CzIPN. As a result, the bi-functional device exhibited a high detectivity of 1.4-×-10 12 Jones under 350-nm UV light. Moreover, our device exhibited efficient EL emission utilizing the merit of reverse intersystem crossing process from triplet to singlet excitons of 4CzIPN, showing a maximum luminance, current efficiency, and power efficiency of 26370-cd/m 2, 8.2-cd/A, and 4.9-lm/W, respectively. This work arouses widespread interest in constructing efficient bi-functional device based on TADF emitter and EAL structure.