Globally, the energy consumed has consistently increased over the last fifty years. Today, most energy is supplied by burning fossil fuels or created using nuclear reactions. These resources are known to have a serious environmental impact, not only in our lifetime but also for future generations. It is, therefore, imperative that alternative energy sources are researched and implemented.
One growing area of research is the organic photovoltaic, a solar cell technology. It has several promising advantages, including its lightweight, large surface area, low cost and robustness.
The organic solar cell can store much larger quantities of solar energy than other solar technologies due to its high optical absorption coefficients. This form of solar power has the potential to rapidly advance the industry, particularly through new research and development activities that will increase their sustainability.
Photovoltaic cell configuration based on organic materials differs from inorganic semiconductors. The most obvious difference are the physical properties of inorganic and organic semiconductors. The organic solar cell, also known as plastic solar cells, use organic materials (carbon-based) in the form of small organic molecules, dendrimers, and polymers, in order to convert solar energy into electrical energy.
The organic solar cells can be made 1000 times thinner than inorganic, silicon solar cells, offering significant savings on materials.
Production and Cost of Organic Solar Cell
The small-molecule organic solar cells use broad-absorption molecules in the visible and near-infrared portion of the electromagnetic range. Highly conjugated arrangements are typically used for the electron donor system such as phthalocyanines and polyacenes. Perylene dyes and C60 are often used as electron-accepting systems. Polymer-based organic solar cells use long-chain molecular systems for the electron-donor material, as well as C60-derived such as the electron acceptor system.
The manufacturing of organic solar system using industrial screen printing has showed the possibility of producing around 1000–100,000 m2 on a process line per day. This is impressive in comparison to the production of silicon solar cells which typically take 1 year to produce a similar surface area. On the other hand, the organic solar cell technology is still new and the estimated cost of manufacturing for purely organic solar cells at a range of $35-$105/m2.
The Current Situation and Future Challenges
The organic solar cells have certain drawbacks, the most significant of which is their low efficiency rates. It is known that organic solar cells have an efficiency of only 5% compared to the 15% silicon cells. In addition to this, they also have a short life. Nevertheless, their many advantages may justify the current international investment and research in the development of new polymer materials, new combinations and new structures to improve efficiency and achieve low cost and large-scale production during the coming years.
The main research challenge will be the creation of cells which are stable in sunlight and able to withstand large temperature variations. The survival of many organic pigments in automotive paints in the sun and the production of organic light-emitting diodes with a lifespan of over 50,000 hours are encouraging signs of the required stability. The final challenge will be to find efficient process and manufacturing solutions in order to create the solar cells at a cost of approximately $30/m2.
The energy consumed to develop a solar cell is less than the amount required for conventional inorganic cells. Therefore, the efficiency of the energy conversion doesn’t necessarily need to be as high as the efficiency of the conventional cell. The extensive use of organic solar cells could help increase the use of solar energy worldwide and reduce human impact on the environment.
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