Unraveling the Discrepancy on Persistent Photoconductivity Between Organic Single-Crystal and Thin-Film Phototransistors

Persistent photoconductivity (PPC) in organic phototransistors (OPTs) offers potential prospects for burgeoning optoelectronic applications. However, a universal comprehend for discrepancy on PPC between organic single-crystal and thin-film phototransistors (OSC-PTs and OTF-PTs) is still a critical challenge hindering its practical applications. A mechanism on the PPC difference related to oxygen-induced charge trapping depth is unveiled in OPTs. Different from the OTF-PTs, oxygen-induced electron capture in OSC-PTs occurs on the top surface of the single crystals, forming a stubborn PPC behavior. This is further verified by applying the different substrate temperature. These findings differ from previous reports and likely provide an original perspective on the design of high-performance OPTs.