| As an inexhaustible green energy, the solar energy is one of the optimal way to resolve energy crisis. In recently years, the heterojunctions composed by semconductor -semconductor and dye-semconductor were widely used to increase the conversion efficiency of the solar energy and the development of the photoelectric devices because the photo-induced charge are easy to separate in these structures. ZnO is an important photoelectric material with high tranmission in the visible region. ZnO is an excllent material to prepare photoelectric devices due to its advantages, such as low cost, low toxicity and rich resource. So, it is worth for us to research. In this paper, we fabricated heterojunctions based on ZnO with p-type NiO and organic dye N719 and investigated the redistribution process of the photogenerated charge by surface photovoltage spectroscopy, which is useful for the application of them in photoelectric conversion. The significant results are listed as follows:1. ZnO and NiO ceramic targets were made with ZnO,NiO powder with the purity of 99.99%, de-ionized water of 18.2 M? and PVA as primary material. First, the PVA and the de-ionized water were mixed at the mass ratio of 1:200, and then heated in water bath at about 90 oC with magenic stirring to make PVA agglomerant. Second, the ZnO or NiO powder were put in agate morear and add some agglomerant to the powder, then whet them exiguous and uniform. Third, the powder is move into the die arrangment and press to moulding, and then the PVA were removed by heating. Last, the targets were put in the chamber furnace and sintered to the ceramic targets.2. ZnO and NiO films were depositd on Si substrates and quartz substrates by laser molecular beam epitaxy technique. The samples were characterized by X-ray diffraction, Raman, photoluminescence and the transmission spectrum. The results indicate that the ZnO and NiO films prepared have good crystallinity and have high transmission in the visible region, which is useful for the fabrication and application of the devices based on ZnO and NiO. 3. ZnO/NiO heterojunction is fabricated on fluorine-doped tin oxide conducting glass substrates by laser-molecular beam epitaxy technique. The samples are characterized by X-ray diffraction, rectification characteristic, UV-visible absorption spectroscopy and surface photovoltage spectroscopy. The all-oxide heterojunction shows clear rectification characteristic with a threshold voltage of about 1.5 V. The photovoltaic response at 373 nm originating from ZnO is enhanced greatly and a new wide photovoltage band from 390 to 600 nm is brought by ZnO/NiO heterojunction. The results show this heterojunction has potential application in photocells and other optoelectronic devices.4. ZnO thin films and (Bu4N)2(Ru)(dcbpyH)2(NCS)2 (called N719) sensitized ZnO thin films are grown on fluorine-doped tin oxide conducting glass substrates using laser molecular beam epitaxy. Ultraviolet-visible absorption, photoluminescence, surface photovoltage spectroscopy, and Raman scattering are employed to probe into the transition process of photogenerated charges and the interaction between ZnO and N719. The experimental results indicate that there is a strong interaction between N719 and ZnO through chemiadsorption. The interaction greatly enhances the photogenerated charge separation and thus the photovoltaic response of the ZnO film but remarkedly weakens its radiative recombination, i.e. photoluminescence, implying strong energy and charge transfer occuring between N719 and ZnO. In addition, a new weak photoluminescence peak observed at about 720 nm is attributed to the electron-hole recombination of N719. |
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