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

Abstract

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.

MXene based saturation organic vertical photoelectric transistors with low subthreshold swing

“…Such geometry provides a nanoscale channel length depending on the thickness of the active layer without complicated lithography process, and results in high current density and working frequency under low operating voltage. The continuous improvement of device performance and the wide application of VOFETs in high-frequency electronics 8 , photodetectors 9 – 11 , synaptic transistors 12 , 13 and organic light-emitting transistors 14 , 15 have proved their great potential in organic electronics.…”

Bipolar Modulation of the Ionic Circuit for Generic Organic Photoelectrochemical Transistor Logic and Sensor

“…Upon illumination, rapid generation and transfer of the photo‐induced excitons could modulate the doping state of the channel and thus the I d . [ 23 ] The second mode chooses to engineer the light‐harvesting gate. Light illumination could redistribute the potential drop between the gate and the channel, changing the doping state of the channel and the I d .…”

Submicron Vertical Channel Organic Electrochemical Transistors with Ultrahigh Transconductance

“…In a slightly different geometry, a vertical channel electrolyte‐gated organic transistor was presented, still with an insulating silicon dioxide (SiO 2 ) spacer separating the top and bottom electrodes, and with a diketopyrrolopyrrole–terthiophene donor–acceptor polymer (PDPP) film forming the channel. [ 21 ] Other inorganic/organic hybrid vertical channel structures were also proposed, [ 22 ] lacking, though, the advantages of a truly microfabricated device.…”