Research : Fabrication and Evaluation of solar cells and thin film transistors

Themes

1. Wavelength conversion films for Solar cell application.
2. Oxide semiconductor Solar cells CuAlO₂/InGaZnO₄
3. Thermoelectric conversion device using FeSi₂, Mg₂Si.
4. Portable and high efficient AC/DC converter for power supply
5. Electric double layer capacitor.
6. Printing solar cells using micron size Si chips
7. Oxide/Inorganic junction solar cells

Fundamentals of solar cells and power generation/storage system

The solar cell industry has grown quickly in recent years due to strong interest in renewable energy and the problem of global climate change and the harmful effect of chemicals on ecological systems. Current solar cells cannot convert all the incoming light into usable energy because some of the light can escape back out of the cell into the air. Sunlight comes in a variety of colors. Lower energy light pass through the cell unused. Higher energy light excites electron to the conduction band, but any energy beyond the band gap energy is lost as heat, and much higher light, more than 3.0 eV, the exited electrons spontaneously recombine with the created holes at or near the surface. We have been trying to fabricating cheaper and more efficient solar cells. We have been focusing on the theme as follows:

1. High efficient wavelength conversion film from UV to VIS light
2. Oxide Semiconductor solar cells for absorbing blue to violet light
3. Printing solar cells using micron size Si particles
4. Oxide/Inorganic junction solar cells

Wavelength conversion films

By converting UV light to VIS.,

(Joint Research with Futaba Corporation since　2009.7-）

We succeeded in fabricating wavelength conversion film from UV to red light.

Oxide semiconductor Solar cells CuAlO₂/InGaZnO₄

Joint research with Hiaki-Lab Department of Applied Molecular Chemistry （2009.4-)

Rectyfying property and photosensitivity have been observed in amorphous CuAlO₂/amorphous InGaZnO₄ structure.

Thermoelectric conversion device using FeSi₂, Mg₂Si

Portable and high efficient AC/DC converter for power supply

We are designing the circuit for high efficient converter with low energy consumption.

Electric double layer capacitor

Printing solar cells using micron size Si chips

Fabrication of paste silicon liquid

Oxide/Inorganic junction solar cells

Oxide semiconductor films and inorganic films are deposited at room temperature onto a transparent plastic substrate

Transparent plastic substrate