Single-crystal strategy towards enhanced carrier mobility of fluorescent molecules for high-efficiency blue OLEDs

The organic single crystal, due to its long-range ordered molecular arrangement, high quality, low defect state density, and excellent luminescent properties, plays an irreplaceable role in the field of optoelectronics and organic light-emitting diodes. By employing strategies for constructing organic single crystals, it is possible to significantly enhance the carrier mobility and stability of devices, leading to superior optoelectronic properties. In particular, in organic light-emitting diode (OLED) devices, the introduction of an organic single crystal luminescent layer can unlock the potential of luminescent materials, extend their operational lifetimes, and enable them to withstand higher current densities. Here, we have grown high fluorescence quantum yield (PLQY) blue-emitting 1,4-bis (2-methylstyryl) benzene (BMSB) molecules in single crystal form. The average mobility has been improved from non-existent in thin films to 0.188 cm2/(V center dot s) in crystal devices. Additionally, through the rational design of device structures and the enhancement of electrical properties, we have achieved a transition from non-functional thin film devices to stable blue-emitting crystal devices, achieving a current density of 853.60 mA/cm2.