High carrier mobility and strong fluorescence emission: Toward highly sensitive single‐crystal organic phototransistors

Abstract Organic single crystals (OSCs) offer a unique combination of both individual and collective properties of the employed molecules, but it remains highly challenging to achieve OSCs with both high mobilities and strong fluorescence emissions for their potential applications in multifunctional optoelectronics. Herein, we demonstrate the design and synthesis of two novel triphenylamine‐functionalized thienoacenes‐based organic semiconductors, 4,8‐distriphenylamineethynylbenzo[1,2‐b:4,5‐b′]dithiophene (4,8‐DTEBDT) and 2,6‐distriphenylamineethynylbenzo[1,2‐b:4,5‐b′]dithiophene (2,6‐DTEBDT), with high‐mobility and strong fluorescence emission. The two compounds show the maximum mobilities up to 0.25 and 0.06 cm 2 V −1 s −1 , the photoluminescence quantum yields (PLQYs) of 51% and 45%, and the small binding energies down to 55.13 and 58.79 meV. The excellent electrical and optical properties ensured the application of 4,8‐DTEBDT and 2,6‐DTEBDT single crystals in ultrasensitive UV phototransistors, achieving high photoresponsivity of 9.60 × 10 5 and 6.43 × 10 4 A W −1 , and detectivity exceeding 5.68 × 10 17 and 2.99 × 10 16 Jones.