Engineering of Interfacial Electron Transfer from Donor–Acceptor Type Organic Semiconductor to ZnO Nanorod for Visible-Light Detection

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

Self-Assembly of Perylenediimide Nanobelts and Their Size-Tunable Exciton Dynamic Properties

Upon the oxidation of perylenediimide dianion precursors, controlled release of neutral units paves the way for the solution-phase self-assembly of nanobelts via synergistic π–π stacking and hydrogen-bonding interactions. The obtained belt size has been regulated through adjusting the precursor supersaturation. This controlled synthesis also offers us an opportunity to explore size-tunable exciton dynamics features in the nanobelt, in which the competitive evolution to H-like exciton or excimer is found to be in strong relevance to the molecular packing and crystal size

Probing the Conformational Transition of 2,2′-Bipyridyl under External Field by Surface-Enhanced Raman Spectroscopy

Investigations on conformational transition of a small organic molecule are important to understand the conformation principles in chemistry and biology. We employed a low-temperature surface-enhanced Raman spectroscopy (LT-SERS) technique to probe the conformational changes of 2,2′-bipyridyl (22BPY) on Ag nanoparticles at the presence of external fields. An electrochemical system was used to provide an electrostatic field, and a special magnet was designed to supply a magneto-static field. High-quality and distinguishable SERS spectra of 22BPY were obtained at the different environments, which show fingerprint labels for correlative conformations of the 22BPY. The conformational transition of 22BPY is implemented via its adsorption on the Ag nanoparticles by triggers of the external electric field and magnetic field