Narrow Band Gap AgInTe2 Solar Cells Fabricated by Printing Method

AgInTe2 micron-particles were synthesized by mechanical ball milling method. Only AgInTe2 phase was obtained in the powder after ball milling from the mixture of elements (Ag, In, and Te). AgInTe2 particles had the variation in the size and the biggest particle was approximately 2 µm. AgInTe2 solar cells were fabricated as superstrate structure by doctor-blade printing, and were annealed at various temperatures under nitrogen ambient. AgInTe2 after annealing showed high crystallinity and two band gaps of 0.67 and 0.86 eV. Although no photocurrent was observed after annealing below 350 °C, the photocurrent was observed in AgInTe2 superstrate solar cells after annealing over 400 °C. The short-circuit photocurrent density strongly increased up to 18 mA/cm2 for the samples annealed at 600 °C for 5 min.Key words: AgInTe2; Solar cells; Printing metho

Lifespan of information service firms in Japan: a survival analysis

The purpose of this paper is an analysis of survival in the Japanese information service industry. Information service firms are generally classified into two typical patterns. One is the group of independent firms such as software vendors, and the other is the group of non-independent such as subsidiaries established by spinning off and so on. We used a sample of 334 firms in Japan and analyzed by Kaplan-Meier estimator method and Cox proportional hazard regression model in order to investigate the difference of survival between these two groups and/or among other attributes. As a result, the lifespan of the information service firms significantly depends on the degree of system integration sales ratio, software development sales ratio, and entrusted processing sales ratio. On the contrary, property of non-independence and high sales ratio with main customers have a negative influence on their survival rates, i.e. lifespan. The paper discusses these results and offers some managerial implications, and future research opportunities are provided

Lifespan of information service firms in Japan: a survival analysis

The purpose of this paper is an analysis of survival in the Japanese information service industry. Information service firms are generally classified into two typical patterns. One is the group of independent firms such as software vendors, and the other is the group of non-independent such as subsidiaries established by spinning off and so on. We used a sample of 334 firms in Japan and analyzed by Kaplan-Meier estimator method and Cox proportional hazard regression model in order to investigate the difference of survival between these two groups and/or among other attributes. As a result, the lifespan of the information service firms significantly depends on the degree of system integration sales ratio, software development sales ratio, and entrusted processing sales ratio. On the contrary, property of non-independence and high sales ratio with main customers have a negative influence on their survival rates, i.e. lifespan. The paper discusses these results and offers some managerial implications, and future research opportunities are provided

Dye-Sensitized Solar Cells Using Surface-Stabilized Nanocrystalline-TiO2 Electrodes Coated by Epoxy Polymer

In order to improve the thermal durability of dye-sensitized solar cells, epoxy polymer was coated on dyed-TiO2 electrode to prevent dye desorption under heating condition over 80 °C.  The covering effect on epoxy polymer was confirmed using impedance spectroscopy.  Using the epoxy polymer coating with Z907 Ru dye and ionic liquid electrolyte, the DSC photovoltaic durability was improved up to 90 °C, which is the highest temperature published for the DSC durability test.  Although the epoxy polymer suppressed the DSC photovoltaic effect, it enhance the thermal durability; DSC coated epoxy polymer on the dyed-TiO2 electrode was able to prolong the efficiency over 90% of the initial value at 90 °C for 550 hours.Key words: Dye-sensitized solar cells; Epoxy polymer; Ionic liquid electrolyte; Thermal durability; Heat tes

Non-Vacuum Process for Production of Crystalline Silicon Solar Cells

Existing technologies for conventional high-efficient solar cells consist of vacuum-processed, high cost, sophisticated, and potentially hazardous techniques (POCl3 diffusion, SiNx deposition, etc.) during crystalline silicon solar cell manufacturing. Alternative research studies of non-vacuum and cost-efficient processes for crystalline silicon solar cells are in continuous demand. However, there is not a well understanding of utilizing schemes and the achievable performances for such applications and techniques in solar cell fabrication. This chapter addresses the non-vacuum processes and applications for crystalline silicon solar cells. Such processes including spin coating and screen-printing phosphorus and boron diffusions for the formation of n+ and p+ emitter or back surface fields, spin coating and spray-deposited antireflection coatings for silicon solar cells. Application techniques were explained by combining and comparing experimental results with the calculation and simulations. Consequently, the aim of this chapter is to provide a good understanding of the non-vacuum processes for crystalline solar cells both with simulation and with experimental proves

Segregation of Cu-In-S Elements in the Spray-Pyrolysis-Deposited Layer of CIS Solar Cells

We report the fabrication of superstrate-structured solar cells by the deposition of Cu-In-S (CIS) films on 〈glass/FTO/TiO2/In2S3〉 under air by spray pyrolysis. The cells had an open-circuit voltage of 0.551 V, a photocurrent density of 9.5 mA/cm2, a fill factor of 0.45, and a conversion efficiency of 2.14%. However, transmission electron microscopy/energy dispersive X-ray (TEM-EDX) analysis revealed significant differences between the atomic ratio of the setting material in the spray-deposition solution and the elements in the layer. Moreover, TEM-EDX measurements suggested strong segregation of the Cu-In-S elements in the spray-pyrolysis-deposited layer. The degree of segregation depended on the substrate (〈glass〉, 〈glass/TiO2〉, or 〈glass/TiO2/In2S3〉), although Cu3In5S9 nanoparticles were segregated in the sulfur layer

Superstrate CuInSe2-Printed Solar Cells on In2S3/TiO2/FTO/Glass Plates

CuInSe2 powders synthesized by ball milling were printed on In2S3/TiO2/FTO/glass substrates, resulting in superstrate solar cells.  Although particle structure of CuInSe2 in the layer remained after heating at 600 °C under N2 gas, photovoltaic effects were observed; the open-circuit voltage and short-circuit current density were 0.45 V and 5.6 mA/cm2, respectively.  The effects of annealing time on the structural, optical and photovoltaic properties of CuInSe2 were studied by scanning electron micrograph (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and UV-Vis reflectance absorption spectroscopy.  The CuInSe2 solar cells were printed in air ambient without vacuum processing and without toxic and explosive chemicals (e.g., hydrazine, H2Se and H2S), which can offer a promising strategy for future research and industrial investigation into cost-effective photovoltaic systems.Key words: Photovoltaic system; Photovoltaic effects; CuInSe2 solar cell