Space charge-induced electrofluorochromic behavior for C12-BTBT-based thin-film devices†

Abstract

An organic field effect transistor (OFET), regarded as one of the next generation flexible devices, is developing towards higher computational power and multi-functionality, for which improvements in charge transport properties and diversified collaborative response need to be achieved. 2,7-Docosenyl[1]benzothiofuran[3,2-b][1]thiophene (C12-BTBT) is an established organic small molecule semiconductor with high mobility. However, the current research on C12-BTBT and its devices only reports photoelectric responses as photodetectors and artificial synapses. The limited stimulus response characteristics restrict its functional expansion, thereby hindering its broader application in flexible sensing, display, and logical computation. Here in this work, the electrofluorochromic (EFC) characteristics of C12-BTBT based transistors are realized and a quantitative fluorescence modulation strategy is proposed based on space charge regulation in the dielectric layer. A reversible switching of the fluorescence intensity ratio over 20 is realized by introducing positive/negative space charge accumulation in polymeric dielectrics, modulated by gate voltage, enabling optical output along with the excellent electrical performance of high field-effect mobility over 9.6 cm² s⁻¹ V⁻¹. Such discovered optical-electrical dual output characteristics are further utilized by establishing a 2-input 2-output integrated logic gate computing system, triggered by UV light and electrical signals as input stimuli, with current response and fluorescence signals serving as output indicators, demonstrating the wide application potential of C12-BTBT devices in molecular logic computation and multi-stimulus sensors.