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

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 ΔE ST indicate that these compounds are candidates for OLED applications.

Highly Deep‐Blue Luminescent Twisted Diphenylamino Terphenyl Emitters by Bromine‐Lithium Exchange Borylation‐Suzuki Sequence

“…Furthermore, they are used as hole transport materials due to high hole transport mobility and low ionization potentials [13,14] . On the other hand, benzonitriles constitute very well‐known acceptor moieties for designing highly luminescent fluorophores [15] . In 2020, Xu et al.…”

“…[13,14] On the other hand, benzonitriles constitute very well-known acceptor moieties for designing highly luminescent fluorophores. [15] In 2020, Xu et al reported a deep-blue emitting compound based on triphenylamine, a benzonitrile acceptor and 9,9-dioctylfluorene as a π-conjugation unit. [16] Another class of blue emitters are spiroconjugated chromophores also including triphenylamines as a structure motif.…”

Highly effective organic light-emitting diodes containing thermally activated delayed fluorescence emitters with horizontal molecular orientation

“…Furthermore, numerous studies have focused on molecular designs utilizing twisted molecular structures among the donor and acceptor units for reducing DE ST and achieving efficient intramolecular charge transfer (ICT) based on pure organic derivatives. 21,22 Meanwhile, despite the development of various TADF emitters with h int of nearly 100%, conventional OLEDs have a 20-25% external quantum efficiency (h ext ) limitation because of low light out-coupling efficiency (h out ). [23][24][25] External and internal optical modication of OLEDs such as attaching a microlens array, optimizing the layer thickness, and refractive index control of the internal layers have been widely studied to increase h out .…”

On the Road Toward More Efficient Biocompatible Two‐Photon Excitable Fluorophores

“…In this work, we proposed to study a new family of quadrupolar dyes by enriching previous cores, to increase their two‐photon absorption properties. Recently, phenoxazine, acridane, phenazasiline and phenothiazine have been used as very efficient donor cores in material chemistry [22–26] . However, these cores have never been extensively studied for their nonlinear properties and we decided to explore their potential to be used as donor cores for two‐photon absorption (Figure 1).…”