Anthracene-[1]benzothieno[3,2-b][1]benzothiophene (BTBT) dyad and triads as p-type semiconductors for organic field-effect transistors and phototransistors

Abstract

[1]Benzothieno[3,2-b][1]benzothiophene (BTBT) and anthracene (An) are the most promising planar building blocks for constructing p-type small molecules for high-performance organic field-effect transistors (OFETs). Herein, we report three novel conjugates, namely, An-BTBT, BTBT-An-BTBT, and An-BTBT-An, which are dyad and triad molecules, by combining An and BTBT units. The differences in photophysical characteristics, molecular packing structures, and charge carrier mobilities of the three compounds were systematically studied. All three compounds display blue fluorescence in tetrahydrofuran (THF) solution, while An-BTBT-An and BTBT-An-BTBT exhibit greenish fluorescence in thin-film state, especially for the BTBT-An-BTBT film, which exhibits a photoluminescence quantum yield (PLQY) of up to 11.6%. Moreover, all three compounds exhibit typical p-type transport properties in polycrystalline OFETs with the lowest mobility for BTBT-An-BTBT (0.22 cm² V⁻¹ s⁻¹) and the highest mobility for An-BTBT-An (1.20 cm² V⁻¹ s⁻¹). Furthermore, An-BTBT-An single crystal OFETs demonstrate the maximum mobility of up to 5.4 cm² V⁻¹ s⁻¹, while the hole mobility of BTBT-An-BTBT single crystals only reaches 0.4 cm² V⁻¹ s⁻¹. Notably, BTBT-An-BTBT single crystals as an active layer in phototransistors exhibit excellent performance, achieving a photoresponsivity of 5375 A W⁻¹ and a photosensitivity up to ∼10⁵.