An easy way to modify the molecular structure of a polymer commonly used in solar cells that can increase solar cell efficiency by over 30 percent has been identified by researchers.
Polymer-based solar cells have two domains, consisting of an electron acceptor and an electron donor material. Excitons are the energy particles created by solar cells when light is absorbed.
"In order to be harnessed effectively as an energy source, excitons must be able to travel quickly to the interface of the donor and acceptor domains and retain as much of the light's energy as possible," said a team researchers from North Carolina State University in the US and Beijing-based Chinese Academy of Sciences.
A team of chemists led by Jianhui Hou from the Chinese Academy of Sciences created a polymer known as PBT-OP.
"PBT-OP was not only easier to make than other commonly used polymers but showed an open circuit voltage (the voltage available from a solar cell) value of 0.78 volts - a 36 percent increase over the 0.6 volt average from similar polymers," said Wei Ma, a post-doctoral physics researcher from NC State University.
The possible drawback in changing the molecular structure of these materials is that one may enhance one aspect of the solar cell but inadvertently create unintended consequences in devices that defeat the initial intent.
"But in this case, we have found a chemically easy way to change the electronic structure and enhance device efficiency by capturing a larger fraction of the light's energy, without changing the material's ability to absorb, create and transport energy," said the study carried in the journal Advanced Materials.