Engineering of Interfacial
Electron Transfer from
Donor–Acceptor Type Organic Semiconductor to ZnO Nanorod for
Visible-Light Detection
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Abstract
Interfacial electron transfer (IET) plays a key role
in photoactive
organic/inorganic hybrid nanomaterials and remains elusive with regard
to interfacial energy level alignment. In this study, we prepared
hybrid ZnO nanorods by grafting n-type perylene bisimide (PBI) derivatives
bearing carboxylic acid groups at nitrogen positions. No evidence
in terms of direct electron transfer from PBI to ZnO can be observed
in PBI/ZnO hybrids. In sharp contrast, incorporation of electron-rich
oligothiophene (<i>n</i>T, <i>n</i> = 1, 2) moieties
into PBI core at bay positions resulted in a highly efficient cascade
IET in <i>n</i>T-PBI/ZnO (<i>n</i> = 1, 2) hybrid
nanorods, which was initiated by photoinduced electron transfer (PET)
from <i>n</i>T (<i>n</i> = 1, 2) to PBI and then
followed by charge shifting from PBI anion to ZnO across the interface.
High performance UV–vis photodetectors based on <i>n</i>T-PBI/ZnO (<i>n</i> = 1, 2) hybrids have been fabricated
and show responsivity of 21.2 and 12.4 A/W and an on/off ratio as
high as 537 and 403, whereas that based on PBI/ZnO shows little visible-light
response. Our results suggest that donor–acceptor type compounds
can be used for constructing photoactive hybrid nanomaterials, in
which efficient cascade IET modifies interfacial electronic structure
and helps extend the spectral response range