Qiaorong Sheng

Electrochemical Growth of Nanopillar Zinc Oxide Films by Applying a Low Concentration of Zinc Nitrate Precursor

Zinc oxide nanopillars with a single crystalline structure on the indium tin oxide substrate were prepared by using an electrodepositing process in lower concentrations of aqueous Zn(NO 3 ) 2 and 0.1 M KCl solutions. Surface structure and crystal orientation of the prepared ZnO films were characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, respectively. By varying the electrolyte composition, the morphology and crystal orientation of ZnO films may be changed dramatically. Well-oriented ZnO nanopillars can be obtained at a relatively low concentration of zinc ion in the electrolyte, and at a lower potential. A bandgap energy change of grown ZnO with different Zn(NO 3 ) 2 concentrations was observed. The effects of electrodepositing potential, deaerating, and annealing are also discussed.

Fabrication and charge/energy-transfer study of 4,7-bis(4-triphenylamino)benzo- 2,1,3-thiadiazole/CuPc composite films

Composite films of 4,7-bis(4-triphenylamino)benzo-2,1,3-thiadiazole (TBT) and copper phthalocyanine (CuPc) are fabricated via protonation-coelectrophoretic deposition from nitromethane solutions of TBT/CuPc mixture in the presence of trifluoroacetic acid as a protonation reagent. A nanospheres–nanowires interpenetrating network structure is obtained when the molar percentage of TBT is 70%. Furthermore, the existence of TBT makes α-phased CuPc be partly transformed into the β-phase, and simultaneously, CuPc disorganizes the TBT unit cells. The blue shift on the absorption edge of TBT and the significant fluorescence quenching in the composite films indicate energy/charge transfer and donor–acceptor (D–A) heterojunction formation. Then these results are proved from another point of view: the mutual overlap of absorption and emission spectra of TBT and CuPc lead to a bidirectional Forster resonance energy transfer at the interface; the molecular energy levels calculated from the results of cyclic voltammetry theoretically determine that there exist a D–A heterojunction and charge transfer from TBT to CuPc. Finally, from the investigation of the field-induced surface photovoltage spectra, it can be concluded that this charge transfer results in efficient dissociation of the photoinduced excitons in the composite films, followed by the generation of a strong photovoltage response.

Nanocrystalline Films Formation of 4,7-Bis(4-triphenylamino)benzo-2,1,3-thiadiazole through Electrophoretic Deposition

The nanocrystalline films of an amorphous triphenylamine derivative have been firstly formed by a facile electrophoretic deposition (EPD) method from a solution of protonated 4,7-bis(4-triphenylamino)benzo-2,1,3-thiadiazole. The films are composed of nanoparticles which diameters are controllably varied from 20 to 200 nm. Compared with spin-coating films, EPD films possess lower band gap and higher energy level of the highest occupied molecular orbital (HOMO), which means superior intermolecular charge-transfer ability and more excellent hole-transporting property. The facile method for preparing nanocrystalline films could also spread to other amorphous triphenylamine derivatives.