The performance of organic solar cells consisting of a donor/acceptor bulk heterojunction has rapidly improved over the past few years.1. Major efforts have been focused on developing a variety of donor materials to gain access to different regions of the solar spectrum as well as to improve carrier transport properties.2 On the other hand, the most utilized acceptors are still restricted to the fullerene family, which includes PC61BM, PC71BM and ICBA.2b, 3 The high cost of fullerenes hinders the potential commercialization of organic solar cells at industrial scale. In comparison to the existing high performing donor materials, the molecule pool of acceptors is still extremely limited, thus inhibiting the further development of organic solar cell in fundamental research and practical application. To that end, the design of new classes of cost-competitive acceptor materials is crucial.However, despite intensive research focused on creating an efficient all polymeric solar cells for the past decade, only three different recipes with PCE only reaching 2% have been reported.4 In recent months, there have been further improvements to the PCE which were up to 3.6%.5 The fundamental understanding of all-polymer solar cells is still in its inceptive stage regarding both the materials chemistry and structure physics. Thus, rational design rules must be utilized to enable fundamental materials understanding of the all polymer solar cells.We report high performance all-polymer solar cells employing polymeric donors and acceptor. Phase separation of the two polymers were fine-tuned by changing backbone of polymeric donors. In fact, we observed a direct correlation between the short circuit current (JSC) and the phase separation size. Additionally, with side chain engineering of the polymeric donor, the phase separation size of the all polymer blends was further reduced. We obtained a record PCE of 4.8%(avarage from 20 devices), with an average  JSC of 9.8 mA cm-2. The highest PCE shoot to 5.0%, with JSC as high as 10.2 mA cm-2, and VOC of 1.02 V. It is the highest performance ever published for an all-polymer solar cell.1. Li, G.; Zhu, R.; Yang, Y., Nat. Photon. 2012 , 6 , 153-161.2. (a) Nelson, J., Mater. Today 2011 , 14 , 462-470; (b) Lin, Y.; Li, Y.; Zhan, X., Chem. Soc. Rev. 2012 , 41, 4245-4272; (c) Chen, J.; Cao, Y., Acc. Chem. Res. 2009 , 42, 1709-1718.3. Sonar, P.; Fong Lim, J. P.; Chan, K. L., Energy Environ. Sci. 2011 , 4, 1558.4. Facchetti, A., Mater. Today 2013,  16 , 123-132.5. Zhou, E.; Cong, J.; Hashimoto, K.; Tajima, K., Advanced Materials 2013 , 25, 6991

Rational design toward high performance all polymer solar cell

248th National Meeting (2014)

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