Dual Mode Radiative Transition from a Phenoselenazine Derivative and Electrical Switching of the Emission Mechanism

Abstract

Dual emission featuring both thermally activated delayed fluorescence (TADF) and phosphorescence was engineered into a single metal-free molecule, phenyl(10-phenyl-10H-phenoselenazin-3-yl)methanone. Selenium incorporated into the molecule increases the spin−orbit coupling to facilitate both TADF and phosphorescence, whereas donor−acceptor units promote TADF emission. The relative contribution of the green TADF and yellow phosphorescence can be controlled by the driving voltage of the devices. At low voltage, phosphorescence emission dominates the electroluminescence, whereas TADF is the major component at high voltages. The mechanism of dual emission was explored using experimental and theoretical methods.

Dehydrogenative C–H Phenochalcogenazination

“…The latter are becoming a research priority in the field of bioactive compounds and, in particular, organic materials and catalysts (Figure ). − …”

Persistent room temperature phosphorescence films based on star-shaped organic emitters

“…RTP materials containing chalcogen atoms have been developed and have shown excellent photophysical properties in recent years. 10,52,56–60 Several persulfurated aromatic compounds with bright green phosphorescence (phosphorescence quantum yield ( Φ P ) up to 100%) in crystal states were first reported by Ceroni et al 61,62 Later on, hexasulfurated, pentasulfurated and tetrasulfurated benzene-cored star-shaped molecules have been designed, synthesized and studied as highly efficient RTP materials. 52,63–67 However, most of them only exhibited rather short phosphorescence lifetime ( τ P < 1 ms).…”

Efficient and tunable purely organic room temperature phosphorescence films from selenium-containing emitters achieved by structural isomerism

“…The development of metal-free purely organic room temperature phosphorescent (RTP) materials with long-lived triplet states and high phosphorescence efficiency has received increasing attention for their potential applications in biological imaging, [1][2][3] optical sensing, [4][5][6] anti-counterfeiting, [7][8][9][10][11] encryption, [12][13][14] and electroluminescence. [15][16][17] Although purely organic RTP materials possess the advantages of low toxicity and cost, facile synthesis and functionalization, and good processability compared to traditional organometallic complexes of heavy metals, [18][19][20][21] their intrinsically weak spin-orbit coupling (SOC) may slow down both the intersystem crossing (ISC) from the lowest excited singlet state (S 1 ) to the triplet states (T n ) and the radiative decay process of the emissive triplet states, which thus can be quenched easily by molecular motions (rotations and vibrations) or quenchers (oxygen and humidity). 22,23 To date, extensive efforts have been devoted to exploring efficient metal-free RTP materials.…”