Molecular Approach to Organic Photovoltaic Devices Enables Low-Cost Production of Highly Efficient and Stable Organic Solar Cells and Panels
These stable, efficient, high-performing organic solar cells are fabricated using a unique “supramolecular assembly” approach. First-generation solar panels, composed of rigid silicon crystal cells, are efficient, but expensive to produce. Thin, flexible second-generation solar panels, made from a wider range of materials, are usually inexpensive, but not very efficient. Using a “supramolecular assembly” approach University of Florida researchers can fabricate organic-based solar cells to achieve high efficiency and stability. Panels made from these cells will combine the efficient solar energy conversion of first-generation solar technology with the low cost of second-generation solar technology. Solar energy is sustainable, renewable and produces zero emissions, making it better for the environment. The global organic photovoltaics market, worth $4.6 million in 2012, is expected to reach $630 million by 2022, which could be further accelerated and expanded with the adoption of this technology.
Supramolecular assembly that enables development of inexpensive, high-performance and stable organic semiconductor based solar cells and panels
- Does not require expensive high-grade silicon often used in conventional solar cells, lowering production costs and possibly leading to the development of disposable solar panels
- Enables the creation of lighter-weight, flexible solar panels that can be produced using high throughput, roll-to-roll manufacturing processes
- Creates ordered pathways for electron-hole migration in a controlled or programmed fashion, leading to improved organic solar cell efficiency and structural stability
- Allows easy integration of previously developed organic light absorbers into the general supramolecular assembly scheme
Most commercially available solar panels are composed of rigid silicon crystal cells that are difficult and costly to manufacture. Flexible thin-film solar cells are much less expensive to manufacture, but do not convert as much sunlight into useable electricity. For more than 15 years, scientists have been experimenting with different materials and fabrication techniques to increase their efficiency to the levels of traditional solar cells. Organic semiconductors including pi-conjugated molecules and polymers have been researched widely for solar cell applications; however, the energy conversion efficiency and stability of organic-based solar cells have not reached commercialization requirements. Researchers at the University of Florida have developed a “supramolecular assembly” approach that improves solar energy conversion efficiency and stability in organic bulk heterojunctions (the photoactive layer in most efficient organic photovoltaic devices). Existing bulk heterojunctions rely on the random organization of two different organic molecular/polymeric species, leading to poorly defined and often unstable networks for electron-hole separation and transport. However, in the supramolecularly assembled bulk heterojunction controlled (or programmed) self-assembly of the organic molecules results in an organic bulk heterojunction structure that secures stable and ordered pathways for electron-hole migration, leading to improved cell efficiency and stability. The supramolecular assembly scheme can be easily extended to include many different conjugated organic molecules for optimal light absorption and voltage output, therefore strongly leveraging the existing development of organic light absorbers. This paradigm shift in fabricating organic solar cells overcomes a critical issue that has limited the development of organic photovoltaic cells, and creates bulk heterojunction organic solar cells that offer the high efficiency of first-generation solar cells and the low cost of second-generation solar cells.