World Community Grid and researchers in Harvard University's Department of Chemistry and Chemical Biology are working together to develop efficient and inexpensive solar cells using organic-based molecular materials, which will help satisfy the world's future energy needs through renewable energy resources.
If the cost of current solar cells was reduced by a factor of five to ten, many countries would likely use solar cells to obtain 20% of their electricity from solar energy. It can reasonably be expected that the cost of manufacturing silicon solar cells could drop by a factor of two to three as the industry grows and economies of scale are realized, but this isn't enough to revolutionize solar cell use.
In light of the emerging need for cheaper solar cells, research in the field of carbon-based or organic solar cells opens the door for low-cost materials and the possibility of a low-cost manufacturing process via high throughput roll-to-roll coating machines (similar to those used to make newspapers). These materials, composed primarily of carbon atoms, can potentially combine the electronic properties of conventional semiconductors with the excellent mechanical and processing properties of plastic materials.
Current organic solar cells have reached power conversion efficiencies of around 5% and lifetimes above 1,000 hours under continuous illumination, close to the values needed to enter the commercial solar cell market in particular niches. Some of the actual organic solar cell market products include: portable battery chargers for cell phones and laptops, emergency power generators, and outdoor gear, such as tents and backpacks. However, to reach a broad market share, and in particular to satisfy the world's energy demand in the year 2050 (see The Clean Energy Project - Phase 1), the efficiencies and lifetimes of these photovoltaics have to be increased substantially. For example, efficiencies on the order of 15% and lifetimes at least larger than 10,000 hours are reasonable expectations for the use of these materials as the principal source of energy for the world in the upcoming years.
KVA SOFT CITIES project with organic photovoltaic rooftop canopies. MITEI and the Government of Portugal. Please see MIT Spectrum, http://www.kvarch.net, and Azure 10 Great Ideas. Photo credit: KVA Matx
World Community Grid and The Clean Energy Project
Grid computing is based on the idea that the world's computing power is no longer concentrated in supercomputer centers, but rather the work is distributed to hundreds of millions of personal computers around the world. Therefore, grid computing is a way to open up new computational resources for the scientific community. On the basis of a collaborative scientific effort, scientists from the Department of Chemistry and Chemical Biology at Harvard University partnered with IBM's World Community Grid and large volunteer member base to use its distributed computing infrastructure, and in December of 2008 launched The Clean Energy Project (see The Clean Energy Project - Phase 1). The importance of this partnership relies on the fact that the enormous computational power of World Community Grid can be deployed to: 1) design thousands of conventional/unconventional materials suitable for organic solar cell applications at the molecular level, and 2) create a public database of molecular structures and photovoltaic properties (as derived from quantum chemistry methods) for researchers to use.
Phase 1 of the project used software called CHARMM to predict how potential candidate molecules pack together to form a solid and to see if this solid's properties are suitable as a candidate for use in solar cells. Phase 2 of the project is using quantum mechanics calculations to more precisely predict if these candidate solids have the needed electronic and physical properties to be useful in making solar cells. These electronic structure calculations will be performed with the Q-Chem quantum chemistry software, developed by Q-Chem, Inc. The hope of the project is to achieve predictive power and provide insight for experimentalists so they can design novel compounds that satisfy the high standards for practical devices: air-stable materials, absorption profiles compatible with the solar spectrum, and high charge-carrier transport characteristics.
Ultimately, with World Community Grid's support, scientists at Harvard University are expecting to create successful materials to produce efficient and inexpensive solar cells that will serve as viable solutions for our future energy needs.