Ultrafast and Stable Organic Single-Crystal Vertical Phototransistor for Self-Powered Photodetection and High-Speed Imaging

Abstract

Organic semiconductor crystals herald new opportunities for fabricating high-performance optoelectronic devices, due to their intrinsic properties including outstanding charge transport properties, long exciton lifetime, and diffusion length. Despite remarkable progress in key figures of merit, the cut-off frequency and responsivity are still lagging behind for most currently reported organic devices. Here, a high-performance broadband vertical phototransistor based on rubrene single crystal, whose response covers the UV to visible range (300–650 nm) is reported. It shows a record-high −3 dB bandwidth of ≈18 kHz and a maximum photoresponsivity of 105 A W−1. Due to the asymmetric Schottky contact and excellent light absorption of organic crystal, the device exhibits excellent zero-bias photoresponse even under ultralow light illumination (≈114 fW). In particular, such organic vertical phototransistor holds good air stability and environmental robustness, and even without any form of encapsulation, no degradation of performance is observed for 2 months continuous operating. In addition, several single-pixel imaging to show its potential for practical applications are demonstrated. The results provide a promising strategy to fabricate ultrafast and sensitive organic photodetectors for future video-frame-rate imaging.