The principle behind every solar cell involves photons from the sun hitting the surface of the cell, where they excite electrons and move them to create a current. Photon energy loss, or the energy loss which occurs during the conversion of photons to electricity, occurs in all types of solar cells. Silicon-based solar cells are known to experience much lower photon energy loss compared to other cells, especially polymer-based plastic solar cells.
Because of this, polymer-based plastic solar cells have not been very popular, despite of their low production cost. The greater loss results in low voltage, and consequently much lower efficiency.
However, a team of scientists from RIKEN Center for Emergent Matter Science and Kyoto University’s Department of Polymer Chemistry, report a major breakthrough. They developed a special polymer, which minimizes the photon energy loss of plastic solar cells, and makes them competitive with silicon-based cells.
The new polymer consists of oxygen atoms that replace the sulfur atoms at the key positions. This resulted in a material that could convert much larger amount of energy from sunlight. In fact, the team reported a conversion efficiency of almost 9% with a high open-circuit voltage.
In order to commercialize their new polymer-based plastic solar cells, the team has to achieve a conversion efficiency of 15% in single-junction cells. Based on their incredible achievement of high open-circuit voltage and high short-circuit current, the guys are more than convinced that it would work.
If this final step is complete, the new invention will change the entire energy sector. This is especially the case since the production of polymer-based plastic solar cells is much less expensive.
More details about the study and the technology can be found in the latest issue of the prestigious journal Nature Communications, with a lead author Kazuaki Kawashima.
Image (c) Kyoto University