第23回名古屋大学年代測定総合研究センターシンポジウム平成22(2010)年度報告

The dominant research subjects are focused on the growth of high quality stoichiometric undoped CuInSe2 epitaxial films by molecular beam epitaxial growth. For MBE growth, it is possible to obtain the high quality epitaxial films and to get the reproducibility and stability of the composition and properties of epilayers by controlling the growth parameters carefully. Under the conditions of fixed Cu molecular beam flux and excess Se molecular beam flux, we can control the In/Cu compositon ratio by changing In molecular beam flux to get stoichiometric and In-rich or Cu-rich epitaxial films. We hope it can be used in the manufacture of solar cell and get high conversion efficiency.

The dominant research subjects are focused on the growth of high quality stoichiometric of CuInSe2 epitaxial films by chemical electrodeposited. For chemical electrodeposited growth, it is possible to obtain the high economical films and to get easier and quicker of the composition and properties by controlling the growth parameters carefully. Under the conditions of fixed copper ion¡]Cu2+¡^concentration and excess indium ion¡]In3+¡^concentration, we can change selenium¡]Se4+¡^ concentration to get films. We hope it could be used in the manufacture of solar cell and get high conversion efficiency.

none

Abstract The objective of this proposed study is to develop the new material CuInSe2 for larger area, low cost and high efficiency commercial CuInSe2 based solar cell for the solar resource in Taiwan. Recently, The¢¹-¢»-¢¾2 ternary chalcopyrite semiconductors, CuMX2(M=In, Ga; X=Se, S) have received considerable potential for nonlinear optics and photovoltaic applications such as a promising material for solar cell. For the request of large area homogeneousness, the electrochemical atomic layer epitaxy (ECALE) and molecular beam epitaxy (MBE) are used to deposit and adjust the composition. The combination of the advantages of MBE and ECALE could produce the large area epitaxial layer and get the precise compositions of CuInSe2 films to obtain a high conversion efficiency for commercial solar cell applications. For the study of large area CuInSe2 substrate, first, the electrochemical atomic layer epitaxy (ECALE) was applied to deposit a layer of CuInSe2 thin film on ITO substrate, and then the physical vapor deposition was applied for the annealing process to adjust the composition wanted. At last, a CuInSe2 epitaxial film was grown on the top of substrate under the MBE process. In addition, under the conditions of fixed In molecular beam flux and excess Se molecular beam flux, we can control the Cu/In composition ratio by changing Cu molecular beam flux to get stoichiometric and In-rich or Cu-rich epitaxial films, and predict the type of conductivity. It could be possible to obtain the high reproducibility and stability of the composition and properties of epilayers by controlling the growth parameters carefully. Finally, We hope it can be used in the manufacture of solar cell and get large area high conversion efficiency.

We use molecular beam deposition (MBD) system to grows bi-layers CuInSe2-based thin film solar cell, soda-lime glass as our substrate, cadmium sulfide(CdS) as our buffer layer, zinc oxide(ZnO) as window layer, Mo as back contact metal and using Al as front contact metal. In our device fabrication process, we primary use physical vapor deposition(PVD) to grows thin film in vacuum condition expect Cadmium sulfide. We already fabricate the CdS/CuInSe2-based thin film solar cell successful. Using current-voltage measurement to get fill factor(F.F.) is 39.76%, open circuit voltage(Voc) is 0.26V and short circuit current(Isc) is 2.104mA in our device. It¡¦s so essential to improve every layers properties in order to get higher quantum efficiencies. Especially, resistivity of the zinc oxide window layer is too high and the interface properties between Al and ZnO is not so good. The junction perfection factor is 1.9161, recombination current is the dominate current. So, research and further improve interface characterization between CuInSe2/CdS is necessary.

none

This paper describes an investigation into the fabrication of absorber layer CuInSe2 films by co-evaporation process. And we used the stainless steel substrates to manufacture Al / ZnO:Al /ZnSe(CdS) / CuInSe2 / Mo /SiO2 / Stainless Steel(SS) flexible thin-film solar cell. In this study, we fabricated the main absorber layer CIS thin film by co-evaporation process including two steps, and CIS thin films parameters were estimated by sheet resistance. Under one-sun (AM1.5,100mW/cm2) conditions solar simulator, we compared the solar cell with different thickness of absorber layer, co-evaporation process and composition to improve solar cell performance. The energy conversion efficiency of the CIS thin-film solar cell (Al/ AZO/ CdS /CIS/Mo/ SLG) was 4.5¢M(Voc =0.38 V¡AJsc = 30.5 mA ¡AFF = 38.6 ¢M), flexible solar cell (Al/AZO/CdS/CIS/Mo/SiO2/SS) was 2.6%( Voc =0.2 V¡AJsc = 41.7 mA ¡AFF = 31.2 %).

The energy issue has been gaining a lot of attention in many countries in recent years. Among the kinds of energies, the solar energy is one of the most interesting topics of them. In addition to the fabrication process and raw material, another focal point aims at solar concentrator. This paper shows a new and easy way to increase the solar energy efficiency. We utilize the micro-optics principle to design and fabricate a microlens array of the solar concentrator. With this concentrator, it can enhance the optical absorption on the solar cell. The microlens array concentrator (MLA-concentrator) is different from the conventional concentrator. The MLA-concentrator does not need any electric equipment to follow the sunlight, and it is easy to manufacture. The size is smaller than conventional concentrator, especially. The MLA-concentrator can decrease the reflection of light at oblique angles and increases the second reflection at the interface between concentrator and solar cell, which makes the sunlight uniform. It also has an interesting characteristic which is the pantoscopic incidence. This new-type MLA-concentrator is fabricated by using LIGA-like process, and then it is integrated to the solar cell for electricity generation. Most important, this kind of structure can be combined with all kinds of solar cell. The solar cell with the MLA- concentrator adds the total watt 3.96% in all angle.

Thesis (Ph.D.)--Murdoch University, 2008. / Thesis submitted to the Faculty of Minerals and Energy. Includes bibliographical references (leaves 238-246)