Surface Doping Effect on the Optoelectronic Properties of Tetrachloro-Substituted Chiral Perylene Diimide Supramolecular Nanowires

In nature, chirality displays itself in diverse forms
and on various
hierarchical scales. Among the various types of chirality, supramolecular
chirality is of particular interest due to its ability to amplify
and induce chirality, which aids in understanding the fundamental
principles of chirality transfer and is also suitable for chirality
applications at the macroscopic scale. Herein, we report the synthesis
of a novel chiral organic semiconductor 2,9-di(hexan-2-yl)anthra[2,1,9-def:6,5,10-d′e′f′]diisoquinoline-1,3,8,10
(2H, 9H)-tetraone (ClCPDI-C6) and
its self-assembly into supramolecular nanowires (NWs). The chirality
of the NWs was successfully transferred via intra- and inter-molecular
interactions from the chiral pendant to the perylene diimide (PDI)
core after self-assembly. Upon exposing the organic NWs to phenylhydrazine
dopant vapor, the average mobility of the NW transistor was increased
from 0.0085 to 0.026 cm2 V–1 s–1. Additionally, phenylhydrazine molecular doping of the NWs significantly
enhanced their optical performance in comparison with the undoped
NWs, with improved photoresponsivity (R) (∼3 times higher), photosensitivity (P) (∼10 times higher), external quantum efficiency
(∼3 times higher), and detectivity (D*) (∼8
times higher). The detectivity of the phenylhydrazine-doped NWs was
1 or 2 orders of magnitude higher than that previously reported for
chiral PDI NWs. Notably, they showed a fast and stable real-time photoswitching
of both undoped and doped ClCPDI-C6 NWs (<90 ms), indicating a
high sensitivity to visible light and great potential in photodetector
and photoswitching applications. From density functional theory calculations,
after absorbing phenylhydrazine on the ClCPDI-C6 NWs, the increased
electron affinity contributes to increased optoelectronic performance.
Our investigation paves the way for future in-depth studies on the
relationship between the structure and supramolecular chirality with
optoelectronic device performance.