Performance improvement of organic phototransistors by using polystyrene microspheres

Organic phototransistors (OPTs) have been intensively studied in recent years due to the combined advantages of phototransistors and organic semiconductors (OSCs). However, the electrical performance of OPTs is largely limited by OSCs themselves, posing a challenge to further improve the performance of the devices. Preparing nano/micro-structures of OSCs is considered as an effective way to improve the performance of OPTs. Polystyrene (PS) microsphere, as a kind of insulating and low-cost material, is extensively used in fabricating nano/microporous structures, and the resulting devices exhibit high response to external stimuli. Therefore, we combined PS microspheres with OSCs to fabricate PS/OSC OPTs, and the Ilight/Idark ratio was enhanced by two orders of magnitude compared with the pristine counterparts, which can be modulated from 46 to 1800 by controlling the diameters of PS microspheres. This strategy paves a way for developing high-performance OPTs with nano/microporous structures with potential applications in organic optoelectronics.