Multifunctional Benzo[4,5]thieno[3,2- b]benzofuran Derivative with High Mobility and Luminescent Properties

Abstract

Development of multifunctional materials and devices has garnered enormous attention in the field of organic optoelectronics; nevertheless, achieving high mobility together with strong luminescence in a single semiconductor remains a major bottleneck. Here, a new multifunctional semiconductor molecule, 2,7-diphenylbenzo[4,5]thieno[3,2-b]benzofuran (BTBF-DPh), that integrates high charge transporting [1]benzothieno[3,2-b][1]benzothiophene with a strongly emissive furan group, is synthesized and applied in three types of optoelectronic devices, including organic light-emitting diodes (OLEDs), organic field-effect transistors (OFETs), and organic phototransistors (OPTs). OLEDs based on BTBF-DPh as the emissive layer showed a blue emission with CIE coordinates of (0.151, 0.069) and a maximum current efficiency of 2.96 cd A^-1 with an external quantum efficiency of 4.23%. Meanwhile, OFETs fabricated with BTBF-DPh thin film manifested a carrier mobility of 0.181 cm² V^-1 s^-1, which is comparable to that of thiophene-based counterparts. Additionally, BTBF-DPh-based OPTs exhibited a maximum responsivity and detectivity of 2.07 × 10³ A W^-1 and of 5.6 × 10¹⁵ Jones, respectively. On the one hand, our rationally designed material, BTBF-DPh, has a dense and close-packed structure with an extended π-conjugation, facilitating charge transport through adjacent molecules. On the other hand, the weakened dipole-dipole interactions between BTBF-DPh molecules that resulted from the unambiguous J-aggregation and reduced spin-orbit coupling caused by replacing sulfur atom significantly suppress the exciton quenching, contributing to the improved photoluminescence performance. These results validate that our newly developed BTBF-DPh is a promising multifunctional organic semiconductor for optoelectronic devices.

Keywords: OFET; OLED; OPT; luminescence; mobility; multifunctionality.