Researchers at the University of California, Los Angeles (UCLA) have achieved a new record of 10.6% for the power-conversion efficiency of an organic polymer solar cell.
Certified by the United States’ National Renewable Energy Laboratory (NREL), the record was achieved using a tandem device to harvest a wider range of the solar spectrum.
Combining multiple p-n junctions sensitive to different wavelengths of light, such tandem devices can achieve higher efficiencies than standard single-junction cells.
Engineers from the UCLA Henry Samueli School of Engineering and Applied Science and the UCLA California Nanosystems Institute constructed a similar tandem device last year that set a record of 8.6%.
But by including an infrared-sensitive polymer material supplied by Japanese chemical company Sumitomo Chemical, the team were able to increase this efficiency by around 2%. The record power-conversion efficiency was confirmed using NREL’s Spectrolab X-25 solar simulator.
Difficulties in the identification of suitable materials had previously hindered the development of these tandem devices. The success of UCLA’s device, using specially designed low and high band-gap polymer materials, is indicative of the potential of tandem polymer photovoltaic cells.
“Everything is done by a very low-cost wet-coating process,” said Professor Yang Yang, who led the UCLA research team. “As this process is compatible with current manufacturing, I anticipate this technology will become commercially viable in the near future.”