It is expected that by the year 2050 the world's energy requirements will double today’s demand. Energy is without doubt a prerequisite for economic stability in both the developed and developing world; despite its current importance, the actual energy system is far from being self-sustainable. Achieving a completely sustainable energy system will require technological breakthroughs that radically change our paradigms on how we produce and use energy. A possible solution to this problem is to use solar energy. Every hour, our sun produces enough solar energy to supply the whole world’s annual energy requirements. Finding the means to convert the incident solar energy into usable forms to maintain the current way of life represents a main objective of The Clean Energy Project team.
Organic solar cells convert sunlight into electricity. The first step is that light must be absorbed in the organic solar cell. This absorbed light causes the electrons in the material to increase their energy. Second, electrons must travel to a region where they can be collected (i.e., the donor-acceptor interface). Once the electrons are collected, they can be extracted to give a current, or they can remain in the device to give rise to a voltage. The electrons that leave the organic solar cell as current can deliver their energy to whatever is connected to the circuit.
Understanding the properties of new materials that are the basis of alternative sources of renewable energy represents one of today’s major scientific challenges. Many of these materials are composed of large organic molecules that contain hundreds of atoms. These atoms can be rearranged in multiple ways to fine-tune the properties of the desired material. With the aid of World Community Grid, researchers will evaluate the conductive properties of at least 100,000 molecular structures (created by combinatorial methods) that are suitable for organic solar cells applications. The results of such an enormous number of computations will be used to create a database of molecular properties for data mining, which will be publicly available.
Solar cells are commonly characterized by the percentage of the incident solar light that they can convert into electrical power. Thus, the efficiency is given as a percentage. In general, the efficiency is determined by the material from which it is made and by the technology used to construct the solar cell. Efficiencies for commercially available solar cells range from about 5% to about 17%. Although inorganic-based solar cells have reached a maximum efficiency of up to 40%, these are expensive to produce and polluting when thrown away. The maximum efficiency reached for an organic-based solar cell is around 6% as of 2007. Therefore, there is still a lot of work to be done to improve them.
If researchers could find an organic-based solar cell whose efficiency reached 10%, these would be commercially feasible and would revolutionize the field of solar materials. Additionally, if these cells covered 0.16% of the surface of the planet, they would produce about an additional 20 TW (Terawatts, a trillion Watts), which will make up for the estimated increase in energy for the year 2050.
The study of solar cells is similar in form to other fields. For instance, the interaction of titania (TiO2) with organic molecules in dye-sensitized solar cells is very similar to (heterogeneous) catalysis, the act of accelerating the rate of a reaction, where a metal particle or surface interacts with an organic molecule or a group of molecules.
Another technological application that will spawn from this project is the study of molecular electronics, where molecules are used for building electronic components. This means that we will potentially provide the means to extend Moore's Law.
Furthermore, the CEP plans to host a range of other calculations for cleaner energy such as work on solar concentrator and fuel cell materials. It is only with your help that researchers can go ahead and try to answer these questions of both pure and applied research.