Plastic solar cell represents a game changer technology, since potentially it can be mass-production via printing technology using earth abundant materials. In this presentation, I will summarize recent achievements of the plastic solar cells, and focus on the rapid progress on the tandem structure. Tandem solar cells provide an effective way to harvest a broader spectrum of solar radiation by combining two or more solar cells with different absorption bands. However, for plastic (or polymer) solar cells, the performance of tandem devices lags behind single-layer solar cells mainly due to the lack of a suitable low-bandgap polymer. Here, we demonstrate highly efficient single and tandem polymer solar cells featuring a low-bandgap conjugated polymer (PBDTT-DPP: bandgap, ∼1.44 eV). A single-layer device based on the polymer provides a power conversion efficiency of ∼6%. When the polymer is applied to tandem solar cells, a power conversion efficiency of 8.62% is achieved. Via further improving of the IR-absorbing polymer, a recording breaking performance of 10.6% was achieved. This approach opens a new direction for achieving high performance polymer solar cells for future commercialization.
Professor Yang Yang is the Carol and Lawrence E. Tannas Jr. Endowed Chair Professor of UCLA. His main research is in the renewable energy with focus on thin film solar cells based on organic polymers and CIGS / CZTS. His group was among the top ten highest cited groups in 2010, according to the Science Watch published by Thomason Reuters'.