Infrared Detection Achieved by Controlling Thermionic Emission in Organic Transistors

Area of Science:

• Materials Science
• Organic Electronics
• Photonics

Background:

• Commercial inorganic infrared (IR) photodetectors are costly and require low temperatures.
• Organic semiconductor (OSC)-based detectors offer room-temperature operation and flexibility but struggle with IR absorption due to wide bandgaps.

Purpose of the Study:

• To develop a cost-effective, room-temperature solution for IR detection using organic field-effect transistors (OFETs).
• To overcome the inherent bandgap limitations of OSCs for direct IR light absorption.

Main Methods:

• Fabrication of OFETs utilizing poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) electrodes.
• Exploiting the photothermal effect of PEDOT:PSS electrodes to induce thermionic emission in OSCs for IR detection.
• Integration of a circuit design to convert invisible IR signals into visible green light.

Main Results:

• The developed OFETs demonstrated a high photosensitivity of 1.42 × 10^5 and a detectivity of 2.12 × 10^8 Jones at 808 nm.
• The devices exhibited a clear IR response across varying light intensities.
• Successful conversion of IR signals to visible light signals was achieved.

Conclusions:

• A universally applicable strategy for achieving IR detection in OFETs based on photothermal effects was established.
• This approach significantly enhances the application potential of OSCs in IR sensing technologies.
• The study presents a viable alternative to traditional inorganic IR detectors.