Best of Both Worlds: Conjugated Polymers Exhibiting Good Photovoltaic Behavior and High Tensile Elasticity

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• 作者：Suchol Savagatrup ; Adam D. Printz ; Daniel Rodriquez ; Darren J. Lipomi
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：March 25, 2014
• 年：2014
• 卷：47
• 期：6
• 页码：1981-1992
• 全文大小：599K
• 年卷期：v.47,no.6(March 25, 2014)
• ISSN：1520-5835

文摘

This paper examines a series of poly(3-alkylthiophene)s (P3ATs), a class of materials for which mechanical compliance and electronic performance have been observed to be in competition. P3ATs with longer alkyl side chains (n 鈮?8) have high elasticity and ductility, but poor electronic performance (as manifested in photovoltaic efficiency in blends with fullerenes); P3ATs with shorter chains (n 鈮?6) exhibit the opposite characteristics. A series of four polymer films in which the average length of the side chain is n = 7 is tested using mechanical, spectroscopic, microscopic, and photovoltaic device-based measurements to determine whether or not it is possible, in principle, to maximize both mechanical and electronic performance in a single organic semiconductor (the 鈥渂est of both worlds鈥?. The four polymer samples are (1) a physical blend of equal parts P3HT and P3OT (P3HT:P3OT, n = 6 and n = 8), (2) a block copolymer (P3HT-b-P3OT), (3) a random copolymer (P3HT-co-P3OT), and (4) poly(3-heptylthiophene) (P3HpT, n = 7). The tensile moduli obtained by mechanical buckling correlate well with spectroscopic evidence (using the weakly interacting H aggregate model) of a well-ordered microstructure of the polymers. The block copolymer was the stiffest of the hybrid samples (680 卤 180 MPa), while P3HpT exhibited maximum compliance (70 卤 10 MPa) and power conversion efficiency in a 1:1 blend with the fullerene PC₆₁BM using stretchable electrodes (PCE = 2.16 卤 0.17%) that was similar to that of P3HT:PC₆₁BM. These analyses may permit the design of organic semiconductors with improved mechanical and electronic properties for mechanically robust and stretchable applications.