Donor鈥揇onor Block Copolymers for Ternary Organic Solar Cells

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• 作者：Lisa M. Kozycz ; Dong Gao ; Jon Hollinger ; Dwight S. Seferos
• 刊名：Macromolecules
• 出版年：2012
• 出版时间：July 24, 2012
• 年：2012
• 卷：45
• 期：14
• 页码：5823-5832
• 全文大小：467K
• 年卷期：v.45,no.14(July 24, 2012)
• ISSN：1520-5835

文摘

We describe a fully conjugated diblock copolymer, poly(3-thiohexylthiophene)-block-(3-hexylthiophene) (P3THT-b-P3HT), which is composed of two equally proportioned blocks that have distinct electronic structure and is suitable for testing in a donor鈥揹onor鈥揳cceptor solar cell. Calculations and optoelectronic characterization demonstrate communication between blocks in silico and in solution. In the solid state, powder X-ray diffraction and atomic force microscopy show that the polymer is semicrystalline and has a distinct morphology (relative to a 1:1 physical blend of its constituent homopolymers), both with and without a fullerene-derivative (PC₇₁BM) acceptor. When tested in a device configuration (P3THT-b-P3HT:PC₇₁BM), the deep HOMO level of the P3THT block increases the open circuit voltage (V_oc) to a value that is equal to a P3THT:PC₇₁BM control device. This shows that the V_oc of an equally proportioned ternary organic solar cell can reach the upper limit of the corresponding binary devices. The block copolymer structure is necessary to maintain favorable active layer morphology. The study shows that donor鈥揹onor block copolymers are excellent materials for organic solar cells and that a high V_oc can be obtained even when the HOMO level of one of the blocks is high.