Improved Tandem All-Polymer Solar Cells Performance by Using Spectrally Matched Subcells
Jianyu Yuan,*1 Michael J. Ford,2 Yalong Xu,1 Yannan Zhang,1 Guillermo C. Bazan,*2 and Wanli Ma*1
1Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Joint International Research Laboratory of Carbon-Based Functional Materials and Devices, Soochow University 199 Ren-Ai Road, Suzhou Industrial Park, Suzhou, Jiangsu 215123, P. R. China
2Center of Polymers and Organic Solids Materials Department University of California Santa Barbara, CA 93106, USA
All-polymer solar cells (all-PSCs) are attractive as alternatives to fabricate thermally and mechanically stable solar cells, especially with recent improvements in their power conversion efficiency (PCE). In this work, efficient all-PSCs with near-infrared response (up to 850 nm) are developed using newly designed regioregular polymer donors with relatively narrow optical gap. These all-PSCs systems achieve PCEs up to 6.0% after incorporating ﬂuorine into the polymer backbone. More importantly, these polymers exhibit absorbance that is complementary to previously reported wide bandgap polymer donors. Thus, the superior properties of the newly designed polymers afford opportunities to fabricate the first spectrally matched all-polymer tandem solar cells with high performance. A PCE of 8.3% is then demonstrated which is the highest efficiency so far for all-polymer tandem solar cells. The design of narrow bandgap polymers provides new directions to enhance the PCE of emerging single-junction and tandem all polymer solar cells.