Novel phenoxazine-benzonitrile and phenothiazine-benzonitrile donor-acceptor molecules with thermally activated delayed fluorescence (TADF)

Faiza Baraket,Bruno Pedras,Érica Torres,Maria João Brites,Mohamed Dammak,Mário N Berberan-Santos

doi:10.1016/j.dyepig.2019.108114

Abstract

Four novel TADF emitters, containing phenothiazine and phenoxazine as electron-donors and benzonitrile derivatives as electron-acceptors were synthesized and fully characterized. Their photophysical (absorption and emission spectra, molar extinction coefficients, fluorescence quantum yields and lifetimes) and electrochemical properties (HOMO and LUMO energy levels) were measured, and drop-cast solid films of the four compounds were obtained to perform TADF studies. The obtained values for ΔEST indicate that these compounds are candidates for OLED applications.

Highlights

Luminescent materials for organic light-emitting diodes (OLEDs) have been an important subject of both academic and industrial research in recent years
The obtained values for ΔEST indicate that these compounds are can didates for OLED applications
Organic fluorescence emitters with Thermally Activated Delayed Fluorescence (TADF) have attracted much attention in that these materials use thermally activated up-conversion of triplet (T1) into singlet (S1) state, giving stable fluorescence with very high fluorescence yields [1–3]. These TADF materials, used in third generation Organic Light Emitting Diodes (OLEDs) by charge-transfer (CT) excited state [4, 5], require a sufficiently small energy gap between the triplet and singlet (ΔEST) to enable up-conversion of the triplet excitons to singlet excitons and realize 100% internal quantum efficiency [6,7] of the exciton for mation generated by electric excitation at S1

Summary

Introduction

Luminescent materials for organic light-emitting diodes (OLEDs) have been an important subject of both academic and industrial research in recent years. Novel phenoxazine-benzonitrile and phenothiazine-benzonitrile donor-acceptor molecules with thermally activated delayed fluorescence (TADF) Berberan-Santos a a CQFM-IN and IBB-Institute for Bioengineering and Biosciences, Instituto Superior T ecnico, Universidade de Lisboa, 1049-001, Lisboa, Portugal b Laboratory of Inorganic Chemistry LR17ES07, Faculty of Sciences of Sfax, University of Sfax, 3000, Sfax, Tunisia c Laborato rio Nacional de Energia e Geologia, I.

Results

Conclusion