Carrier‐Transport Mechanism in Organic Antiambipolar Transistors Unveiled by Operando Photoemission Electron Microscopy. Issue 30 (19th June 2022)

• Record Type: Journal Article
• Authors: Hayakawa, Ryoma; Takeiri, Soichiro; Yamada, Yoichi; Wakayama, Yutaka; Fukumoto, Keiki
• Is Part Of: Advanced materials. Volume 34:Issue 30(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-06-19
• Subjects: carrier transport -- lateral p–n junctions -- negative differential transconductance -- organic antiambipolar transistors -- photoemission electron microscopy; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202201277
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Organic antiambipolar transistors (AATs) have partially overlapped p–n junctions. At room temperature, this p–n junction induces a negative differential transconductance in an AAT. However, the detailed carrier‐transport mechanism remains unclear. Herein, an operando photoemission electron microscopy is used to tackle this issue owing to the technique's ability to visualize conductive electrons in real time during transistor operation. Notably, it is observed that when the AAT is on, a depletion layer forms at the lateral p–n junction. The visualized depletion layer shows that both p‐ and n‐type channels have pinch‐off states in the gate voltage range when the AAT is in on state. The steep potential gradient at the lateral p–n interface enhances the electron conduction from n‐type to p‐type semiconductor. Another significant finding is that most electrons are considered to recombine with the accumulated holes in the p‐type semiconductor, affording the reduction of photoemission intensity by ≈80%. This technique provides a thorough understanding of carrier transport in AATs, further improving the device performance. Abstract : The carrier transport in an organic antiambipolar transistor (AAT) is examined using operando photoemission electron microscopy. The approach visualizes the conductive electrons under the actual transistor operations and reveals that a lateral p–n junction is crucial for the negative differential transconductance in the AAT. These results help in enhancing the device's performance.