There are currently many research groups active in the field of photovoltaics in universities and research institutions around the world. This research can be divided into three areas.
- Making current technology solar cells cheaper and more efficient.
- Developing new technologies based on new solar cell architectural designs.
- Developing new materials to serve as light absorbers and charge carriers.
Ancient Solar Module
But the recent development is...
Many new solar cells use transparent thin films that are
also conductors of electrical charge. The dominant conductive thin films used
in research now are transparent conductive oxides (abbreviated
"TCO"), and include fluorine-doped tin oxide (SnO2:F, or
"FTO"), doped zinc oxide (e.g.: ZnO:Al), and indium tin oxide
(abbreviated "ITO"). These conductive films are also used in the LCD
industry for flat panel displays. The dual function of a TCO allows light to
pass through a substrate window to the active light-absorbing material beneath,
and also serves as an ohmic contact to transport photogenerated charge carriers
away from that light-absorbing material. The present TCO materials are
effective for research, but perhaps are not yet optimized for large-scale
photovoltaic production. They require very special deposition conditions at
high vacuum, they can sometimes suffer from poor mechanical strength, and most
have poor transmittance in the infrared portion of the spectrum (e.g.: ITO thin
films can also be used as infrared filters in airplane windows). These factors
make large-scale manufacturing more costly.
Transparent Solar module
Materials used in Transparent Module
A relatively new area has emerged using carbon nanotube networks as a transparent conductor for organic solar cells. Nanotube networks are flexible and can be deposited on surfaces a variety of ways. With some treatment, nanotube films can be highly transparent in the infrared, possibly enabling efficient low-bandgap solar cells. Nanotube networks are p-type conductors, whereas traditional transparent conductors are exclusively n-type. The availability of a p-type transparent conductor could lead to new cell designs that simplify manufacturing and improve efficiency.
A relatively new area has emerged using carbon nanotube networks as a transparent conductor for organic solar cells. Nanotube networks are flexible and can be deposited on surfaces a variety of ways. With some treatment, nanotube films can be highly transparent in the infrared, possibly enabling efficient low-bandgap solar cells. Nanotube networks are p-type conductors, whereas traditional transparent conductors are exclusively n-type. The availability of a p-type transparent conductor could lead to new cell designs that simplify manufacturing and improve efficiency.
