High-Performance All-Solution-Processed Flexible Photodetector Arrays Based on Ultrashort Channel Amorphous Oxide Semiconductor Transistors.

Amorphous oxide semiconductor (AOS) field-effect phototransistors (FEPTs) are promising candidates for emerging photodetectors. Unfortunately, traditional lateral AOS FEPTs suffer from low photosensitivity, slow response time and inadequate mechanical flexibility, which restrict their widespread commercial application. In this work, novel AOS-based vertical field-effect phototransistor (VFEPT) arrays are presented, where the semiconducting layer and source and drain electrodes are deposited by inkjet printing. Benefitted from the unique vertical structure and ultrashort channel length, the exciton dissociation, carrier transfer, and collection efficiency were dramatically enhanced, resulting in excellent photoelectric performance in VFEPT devices, which was better than that of the traditional lateral AOS phototransistors. Moreover, flexible AOS VFEPT arrays were investigated for the first time on polyimide substrates. Due to the unique vertical architecture, the carrier transport was negligibly affected by the strain-induced in-plane cracks of the semiconductor channel layer during the mechanical bending process, which overcame the maximum bending limit of traditional lateral AOS thin-film transistors to ensure a transistor technique that gives notable mechanical robustness against repeated mechanical bending. Hence, this work provided a new pathway in emerging applications for AOS photodetectors with sensitivity, transparency, and flexibility.