Breakthrough near on solar electricity
The reactions occurring in solar cells are studied with fast
spectroscopy whose measurement accuracy is as high as
The amount of sunlight reaching the Earth's surface in 1.5 hours contains enough energy to meet the world's energy demand for an entire year. Researchers all over the world have set their sights firmly on the Sun as a future source of energy. TUT conducts research into solar energy in close cooperation with international partners.
"The world's first solar cells were created 50 years ago. Even though the field has made great progress since then, many questions remain unanswered. The main challenge is the development of solar cell technology to allow mass production," says Professor Helge Lemmetyinen from the Department of Chemistry and Bioengineering at TUT.
Last spring, the Swiss scientist Michael Grätzel received the world's largest technology prize, the Millennium Technology Prize. Grätzel has developed a solar cell with a sensible price-performance ratio.
"The prize went to the right person! It also demonstrates that solar energy is understood and accepted as an important part in our quest for alternative energy sources that could replace fossil fuels," says Lemmetyinen.
The Photochemistry Research Group at the Department, headed by Helge Lemmetyinen, has conducted research into solar energy at TUT since the mid-1990s. At the moment, the group is working on seven projects in the field.
"We carry out fundamental research with an eye to develop photonics applications. The group is part of an international community of researchers developing low-cost, high-efficiency solar cells, in which Grätzel and his team are also involved. The community members are active in reporting their findings to each other, because the problems can only be solved through international collaboration. You could say that we're all picking berries into one basket," compares Lemmetyinen.
Mimicking natural mechanisms
Future solar cells could be, for example, integrated into the outer wall structure of buildings to produce residential energy. To turn this vision into reality, researchers need to develop alternatives for conventional silicon-based solar cells that are expensive and time-consuming to produce.
Photonics seeps into everyday life
Solar cell research falls under the field of photonics that examines the interaction between light and matter and how light is generated, detected and its direction controlled. Photonics is closely related to optics and optoelectronics.
Along with solar panels and cells, typical examples of photonics applications are screens, laser devices, barcode scanners, CD and DVD players, optical fibres and LEDs.
The European Commission has defined photonics as a key enabling technology. Photonics, and especially nanophotonics that focuses on the optical properties of nanomaterials, is one of the fastest growing research fields worldwide.
At TUT, photonics research is undertaken at the Department of Chemistry and Bioengineering, the Department of Physics and the Optoelectronics Research Centre (ORC).
The Department of Chemistry and Bioengineering and the Department of Physics mainly conduct fundamental photonics research. ORC works in close cooperation with industry and strives to develop applications at a rapid pace. ORC develops, among others, high-efficiency solar cells based on semiconductor technology.
The current line of research was inspired by the natural interaction between light and materials.
"Solar cells that are made of organic materials convert the Sun's energy into electricity by mimicking photosynthesis, the process whereby green plants produce carbohydrates and oxygen. This is also the idea behind the dye-sensitized Grätzel cell made on porous titanium oxide. The solution has definite potential but cell technology is still in its early stages, thinking the possibilities" says Lemmetyinen.
The latest project led by Lemmetyinen, New Photoactive Materials for Organic Solar Cells, received 360,000 euros of funding from the Academy of Finland in spring 2010. The project explores the relationship between molecular structures, photophysics and the photoelectric effect. The group's partner in the project is the photochemistry research group at Kyoto University, with which Lemmetyinen's group has a long-standing tradition of collaboration.
"The group has succeeded in building solar cells with an efficiency of 6.5 percent. We're looking to double the efficiency to make solar energy a competitive alternative for other sources of energy," says Lemmetyinen.
Did you know?
The Academy of Finland is currently running a research programme dubbed "Photonics and Modern Imaging Techniques" spanning from 2010 to 2013. The programme aims at raising photonics as one of Finland's leading research fields on a global scale. Of the total 13 projects included in the research programme, TUT is involved in six. The Academy of Finland is also funding international collaboration projects within the framework of the programme. In addition to the solar cell project headed by Professor Helge Lemmetyinen, the group led by Professor Martti Kauranen at the Department of Physics also received 360,000 euros to conduct research into metal-dielectric hybrid materials used in the local, temporal and spectral control of ultrafast pulses. The group's research partner is a laser institute based in Tokyo.