| AVS 62nd International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS-TuP |
| Session: | Surface Science Poster Session |
| Presenter: | Tomokazu Tsuchiya, Kogakuin University, Japan |
| Authors: | T. Tsuchiya, Kogakuin University, Japan I. Takano, Kogakuin University, Japan |
| Correspondent: | Click to Email |
As one solution to the power shortage and global warming, a renewable energy such as solar cells is desired. Furthermore the high purity silicon that is the main raw material for solar cells is insufficient worldwide, and so new solar cells without silicon that are able to be replaced to silicon-based solar cells have been required. Practical application of oxide-based thin film solar cells is expected in reduction of the energy cost or the environmental load.
Generally a typical oxide-based thin film solar cell is a wet dye-sensitized solar cell composed of an electrolyte, an electrode of a titanium oxide and a sensitizing dye. Recently a solid-state dye-sensitized solar cell which uses metal oxides instead of an electrolyte has been studied. In our previous study on TiO2/Cu2O solid-state dye-sensitized solar cells, the main problem was Cu diffusion from the under layer Cu2O. The diffusion of Cu to a titanium oxide layer induced the collapse of p-n junction.
The NiO thin film is used as a transparent oxide semiconductor. Most of the transparent oxide semiconductors are an n-type semiconductor, while NiO is a p-type semiconductor. In this study, we used NiO as a barrier layer between TiO2 and Cu2O for preventing the diffusion of Cu, and we investigated the characteristics of Cu2O/NiO/TiO2 solar cells.
Cu2O/NiO/TiO2 solar cells were fabricated by reactive magnetron sputtering. As substrates, the glass (Corning#1737) and an ITO-film coated glass were ultrasonically cleaned by acetone. The NiO thin film was deposited on those substrates by using pure metallic nickel (99.99%) as a sputtering target material in an oxygen gas atmosphere. The flow rate of an argon gas for sputtering was 20 sccm. The flow rate of an oxygen gas was 2.7 sccm. A thickness of the NiO layer was changed from 2 nm to 50 nm. On the other hand the fundamental preparations of the Cu2O layer and the TiO2 layer were performed by 200 nm in a thickness through 15 sccm and 20 sccm in an argon gas, and 10 sccm and 2.3 sccm in an oxygen gas, respectively.
Cu2O/NiO/TiO2 solar cells were successfully fabricated by reactive magnetron sputtering. The solar cell with the NiO layer of 4 nm thickness showed the maximum conversion efficiency of 5.6×10-3 % which was 9 times compared with the sample without the NiO layer.