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Photoconductance from the Bent-to-Planar Photocycle between Ground and Excited States in Single-Molecule Junctions.

Photoconductance from the Bent-to-Planar Photocycle between Ground and Excited States in Single-Molecule Junctions.

Authors :
Zou Q
Chen X
Zhou Y
Jin X
Zhang Z
Qiu J
Wang R
Hong W
Su J
Qu DH
Tian H
Source :
Journal of the American Chemical Society [J Am Chem Soc] 2022 Jun 08; Vol. 144 (22), pp. 10042-10052. Date of Electronic Publication: 2022 May 25.
Publication Year :
2022

Abstract

Single-molecule conductance measurements for 9,14-diphenyl-9,14-dihydrodibenzo[ a , c ]phenazine ( DPAC ) may offer unique insight into the bent-to-planar photocycle between the ground and excited states. Herein, we employ DPAC derivative DPAC-SMe as the molecular prototype to fabricate single-molecule junctions using the scanning tunneling microscope break junction technique and explore photoconductance dependence on the excited-state structural/electronic changes. We find up to ∼200% conductance enhancement of DPAC-SMe under continuous 340 nm light irradiation than that without irradiation, while photoconductance disappears in the case where structural evolution of the DPAC-SMe is halted through macrocyclization. The in situ conductance modulation as pulsed 340 nm light irradiation is monitored in the DPAC-SMe -based junctions alone, suggesting that the photoconductance of DPAC-SMe stems from photoinduced intramolecular planarization. Theoretical calculations reveal that the photoinduced structural evolution brings about a significant redistribution of the electron cloud density, which leads to the appearance of Fano resonance, resulting in enhanced conductance through the DPAC-SMe -fabricated junctions. This work provides evidence of bent-to-planar photocycle-induced conductance differences at the single-molecule level, offering a tailored approach for tuning the charge transport characteristics of organic photoelectronic devices.

Subjects

Subjects :
Electronics
Nanotechnology

Details

Language :
English
ISSN :
1520-5126
Volume :
144
Issue :
22
Database :
MEDLINE
Journal :
Journal of the American Chemical Society
Publication Type :
Academic Journal
Accession number :
35611861
Full Text :
https://doi.org/10.1021/jacs.2c03671