Assistant professor Qiquan Qiao in South Dakota States Center for Advanced Photovoltaics in the U.S. has received the NSF Career award. He said the project deals with organic photovoltaics (PV), or solar cells, assembled from carbon-based polymers instead of traditional solar cells that rely on inorganic, or non-carbon, materials such as silicon. Organic materials have the advantage of being inexpensive, but to date they have also been less efficient than traditional solar cells, he said.
Organic PV are currently based primarily on conducting polymers with characteristics scientists describe as short lifetime excited states and short diffusion lengths. Those limitations mean the polymers have low efficiencies, currently in the range of 6 to 7 percent, Qiao explained.
With better materials and more efficient designs, organic solar cells could reach 10 to 15 percent efficiency, he added. Specifically, he wants to develop new long-lifetime excited state polymers; then design solar cells with such materials. Such a design would mean that the electrons excited as the polymer absorbs sunlight would remain in that state longer, he believes, which gives the PV device a longer window of time to harvest the excited state electrons.
The proposed work will potentially reveal some of the bottlenecks, which have hampered high-efficiency polymer solar cell development, by providing a completely different avenue to the losses and limitations in the current singlet-based polymers and devices, Qiao said. This is one of the possible ideas for design that potentially would increase efficiency.
Qiaos project also would promote teaching and learning at all educational levels, involving participation by K-12 students, as well as undergraduate and graduate students. He plans to develop an education-based polymer PV lab station for the South Dakota Mobile Science Lab. The Mobile Science Lab travels to schools around the state during the school year.
The primary purpose of the Mobile Science Labs is to provide South Dakota students with an opportunity to perform science lab activities with advanced equipment, technology and methods that are usually not available in small schools, he concluded.