Dual-Band, High-Performance Phototransistors from Hybrid Perovskite and Organic Crystal Array for Secure Communication Applications

High-performance phototransistors made from organic semiconductor single crystals (OSSCs) have attracted much attention due to the high responsivity and solution-processing capability of OSSCs. However, OSSC-based phototransistors capable of dual-band spectral response remain a difficult challenge to achieve because organic semiconductors usually possess only narrow single-band absorption. Here, we report the fabrication of high-performance, dual-band phototransistors from a hybrid structure of a 2,7-dioctyl[1]benzothieno[3,2- b][1]benzothiophene (C8-BTBT) single-crystal array coated with CH₃NH₃PbI₃ nanoparticles (NPs) synthesized by a simple, one-step solution method. In contrast to C8-BTBT and CH₃NH₃PbI₃ NPs with respective absorption in the ultraviolet (UV) and visible (vis) region, their hybrid structure shows broad absorption covering the entire UV-vis range. The hybrid-based phototransistors exhibit an ultrahigh responsivity of >1.72 × 10⁴ A/W in the 252-780 nm region, which represents the best performance for solution-processing, broadband photodetectors. Moreover, integrated phototransistor circuitries from the hybrid CH₃NH₃PbI₃ NPs/C8-BTBT single-crystal array show applications for high-security communication.