Vertical Channel Inorganic/Organic Hybrid Electrochemical Phototransistors with Ultrahigh Responsivity and Fast Response Speed

• DOI: 10.1021/acsami.0c20704
• Publication Date: 2021-02-06T11:58:30Z
• Authors: Yujie Yan; Qizhen Chen; Xiumei Wang; Yaqian Liu; Rengjian Yu; Changsong Gao; Huipeng Chen; Tailiang Guo
• Keywords: photoresponse threshold properties; Kelvin probe microscopy; Physiology; Science Policy; VECPT; ultrahigh photoresponsivity; 02 engineering and technology; channel capacitance; nanoscale channel length; 7. Clean energy; OPT; optoelectronic performance; photosensing mechanism; nanoscale channel length device system; Space Science; transconductance; electrochemical phototransistors; Vertical Channel; nanoscale channel; photo-generated carriers; 1 V; electrochemical phototransistor; Molecular Biology; fast-speed response; Ecology; channel length; field-effect transistors; FET; undesired amplification; 600; Ultrahigh Responsivity; light monitoring system; device systems; response speed; Fast Response Speed Organic phototr.; light-emitting diode; optoelectronic performances; photocurrent output; 0210 nano-technology; Neuroscience; Biotechnology; Biological Sciences not elsewhere classified

Organic phototransistors (OPTs) have attracted enormous attention because of their promising applications in sensing, communication, and imaging. Currently, most OPTs reported utilize field-effect transistors (FETs) with relative long channel length which usually has undesired amplification because of their inherent low transconductance originated from their low channel capacitance, limiting the further improvement of performance. Herein, a vertical channel hybrid electrochemical phototransistor with a nanoscale channel and large transconductance (VECPT) is invented for the first time to achieve ultrahigh photoresponsivity along with a fast response speed. Benefiting from the nanoscale channel length and large transconductance, the photo-generated carriers in channel can be efficiently dissociated, transported, and amplified into the enlarged photocurrent output. Therefore, the devices deliver substantially improved optoelectronic performances with a photoresponsivity as high as ≈2.99 × 107 A/W, detectivity of ≈1.49 × 1013 Jones, and fast-speed response of ≈73 μs under a low voltage of 1 V, which are superior to those of the reported OPTs based on FETs. Moreover, the in situ Kelvin probe microscopy is performed to characterize the surface potential of device systems for better elucidating the photosensing mechanism. Furthermore, taking advantage of its excellent optoelectronic performance, an ultraviolet light monitoring system is constructed by integrating VECPT with a light-emitting diode, which also shows the real-time, high-sensitive, and controllable photoresponse threshold properties. All these results demonstrate the great potential of these electrochemical phototransistors and provide valuable insights into the design of the nanoscale channel length device system for high-performance photodetection.