A phenothiazine derivative of FCO-CzS with changeable mechanoluminescence is reported, which, upon continuous mechanical stimulus, shows mechanoluminescent emission from blue to white and yellow. Careful analysis of the experimental results, coupled with the well-understood photoluminescence theory, show that the molecular conformation transition of the phenothiazine group from quasi-axial to quasi-equatorial is responsible for this dynamic mechanoluminescence effect.

Ap henothiazine derivative of FCO-CzS with changeable mechanoluminescence is reported, which,u pon continuous mechanical stimulus,s hows mechanoluminescent emission from blue to white and yellow.Careful analysis of the experimental results,c oupled with the well-understood photoluminescence theory,s how that the molecular conformation transition of the phenothiazine group from quasi-axial to quasi-equatorial is responsible for this dynamic mechanoluminescence effect.

Organic luminogens with strong solid-state emission have attracted much attention for their widely practical applications. However, the traditional organic luminogens with planar conformations often suffer from the notorious aggregation-caused quenching (ACQ) effect in solid state for the π–π stacking. Here, a highly efficient blue emitter TPE-4Py with an aggregation-induced emission (AIE) effect is achieved by combining twisted tetraphenylethene (TPE) core and planar pyrene peripheries. When the emitter was spin-coated in non-doped OLEDs with or without a hole-transporting layer, comparable EL performance was achieved, showing the bifunctional property as both an emitter and a hole-transporting layer. Furthermore, its EL efficiency was promoted in doped OLED, even at a high doping concentration (50%), because of its novel AIE effect, with a current efficiency up to 4.9 cd/A at 484 nm.

It is well-known that the electrically generated excitons can perform the spin evolution between high-lying excited states, providing an efficient way to utilize triplet excitons in organic light-emitting diodes (OLEDs). Anthracene families offer an opportunity to deeply investigate the processes of triplet excitons on high-lying excited states in detail. Here, a simplified model is proposed to study the exciton dynamics in anthracene derivatives-based devices. The mechanism on the processes of high-energy level intersystem crossing in anthracene derivatives is well revealed by theoretical calculation, transient electroluminescence, transient photoluminescence, and transient absorption spectrum measurements. Besides, doping strategy is proposed to suppress the exciton loss channel for improving the efficiency of devices. The studies establish an in situ method to evaluate the apparent singlet exciton formation ratio in devices due to the exciton evolution between high-lying excited states and offer some clues to further utilize these triplet excitons, thus improving the efficiency of the resulting fluorescence OLEDs in the future.