π-Conjugated p-type PBDB-T and n-type N2200 macromolecular units are alternatively bonded to generate ambipolar copolymer (i.e. P(BDBT-co-N2200)) for achieving donor-acceptor (D-A) heterojunction. From the laser confocal microscope photoluminescence (PL) spectra of the P(BDBT-co-N2200) copolymer, PL characteristic peaks of PBDB-T and N2200 are simultaneously observed at 695, 760, and 860 nm. The thin-film transistors (TFTs) using P(BDBT-co-N2200) copolymer show ambipolar transistor characteristics originating from the coexistence of p-type and n-type semiconducting macromolecular units. Interestingly, a high hysteresis is observed in the transfer and output characteristics of the TFTs because of the interface traps and near-interface bulk traps. Under light irradiation, distinctive photocurrents and hysteresis are observed, suggesting the optically mediated charge release and photogating effects caused by trap states. Charge trapping with a high hysteresis and photoconduction with the photogating effect of the P(BDBT-co-N2200)-based ambipolar TFTs induce stable and repeatable writing, reading, and erasing operations. The optoelectronic memory devices using the P(BDBT-co-N2200)-based ambipolar TFTs are realized with the merit of a long charge storage time of 40 s. The π-conjugated copolymer, P(BDBT-co-N2200) exhibiting D–A heterojunction, can be applied to multifunctional devices, such as photoresponsive ambipolar transistors and optoelectronic memory devices, for image sensing and data storage.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government [No. 2021R1A2C2005885 , 2019R1A6A1A11044070 , 2021R1A6A1A03039696 ], and BK21.
© 2022 Elsevier B.V.
- Ambipolar transistor
- Conjugated polymer
- Donor–acceptor heterojunction
- Optoelectronic memory
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Materials Chemistry
- Electrical and Electronic Engineering