Ryo Akiike

Development of Novel Al-Doped Zinc Oxide Films Fabricated on Etched Glass and Their Application to Solar Cells

We have successfully developed novel aluminum-doped zinc oxide (AZO-X) films with a high haze ratio by the combined use of an etched glass substrate and wet-etched AZO-X films. The effects of the use of an etched glass substrate and wet-chemical etching on the properties of AZO-X films were investigated. The texture size and rms roughness of these films largely increased with glass surface roughening. Post-treatment using wet chemical etching slightly increased the texture size and rms roughness. The etched glass approach has been found to be a promising method for achieving an AZO-coated glass substrate with a high haze ratio. Using high-haze ratio AZO-X films as the front transparent conductive oxide (TCO) layers in solar cells, we improved the quantum efficiency (QE) of these solar cells particularly in the long-wavelength region. Thus, the AZO-X films deposited on etched glass have a high potential for use as front TCO layers in silicon-based thin-film solar cells.

Development of Novel Aluminum-Doped Zinc Oxide Film and Its Application to Solar Cells

We have developed novel aluminum-doped zinc oxide films (AZO-X and AZO-HX films) with a high haze value using wet-chemical etching for various times after dc magnetron sputtering, and have investigated their electrical and optical properties, durability under high-humidity condition, and surface morphology. The AZO-X and AZO-HX films showed good balance between transmittance in the near-infrared area and durability under 85 °C–85%RH condition. These novel films also had a higher haze value after wet chemical etching than normal AZO films. The crater size and haze value of the AZO-HX film increased with increasing etching time in comparison with those of the AZO-X film. The haze value of the AZO-HX film was higher than that of the AZO-X film; their values are 90% at 550 nm and 60% at 800 nm. Furthermore, the AZO-HX film was applied in amorphous silicon (a-Si) single-type solar cells as the front electrode. The short-circuit current of the solar cell using the AZO-HX film was higher than that of the solar cell using the AZO-X film. As an optimization-based result, an efficiency as high as 10.2% was obtained, showing that the new AZO-HX film is a promising material for the front electrode of a-Si solar cells.

Development of novel Al doped zinc oxide film and its application to solar cells

We have developed novel Al doped zinc oxide (AZO) films, AZO-X films, using d.c. magnetron sputtering process and have investigated their electro-optical properties and their surface morphology. AZO-X films showed a good balance between the transmittance in near-infrared area and the durability under 85°C-85%RH condition. And AZO-X film also had higher haze value after wet chemical etching than the value obtained in normal AZO film. Furthermore, AZO-X films have been applied to amorphous Si (a-Si) single-type solar cells as the front electrodes. The efficiency as high as 10.1% with high short-circuit current has been obtained, showing that this novel AZO-X is the new promising material for front electrode of a-Si solar cells.