Influence of Incorporating Different Electron-Rich Thiophene-Based Units on the Photovoltaic Properties of Isoindigo-Based Conjugated Polymers: An Experimental and DFT Study

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• 作者：Wenliu Zhuang ; Margherita Bolognesi ; Mirko Seri ; Patrik Henriksson ; Desta Gedefaw ; Renee Kroon ; Markus Jarvid ; Angelica Lundin ; Ergang Wang ; Michele Muccini ; Mats R. Andersson
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：November 12, 2013
• 年：2013
• 卷：46
• 期：21
• 页码：8488-8499
• 全文大小：632K
• 年卷期：v.46,no.21(November 12, 2013)
• ISSN：1520-5835

文摘

A series of novel donor鈥揳cceptor conjugated alternating copolymers based on the isoindigo acceptor moiety have been designed, synthesized, and characterized, in order to explore the potential of isoindigo for efficient donor materials with high photovoltages in solar cells. We have systematically investigated and discussed the effect of combining different electron-rich thiophene-based units on the structural, optical, electronic, and photovoltaic properties of the resulting polymers. Morphological studies and quantum-chemical calculations are carried out to gain insights into the different properties. The power conversion efficiencies (PCEs) of the solar cells based on these polymers are increased step by step by over 3-fold through a rational structural modification. Among them, PBDTA-MIM shows a PCE of 5.4%, which is to our knowledge the best result achieved among isoindigo-based polymers for solar cells combined with PC₆₁BM as the acceptor using the conventional device configuration. Our results further emphasize the use of isoindigo as an effective acceptor unit and highlight the importance of carefully choosing appropriate chemical structure to design efficient donor鈥揳cceptor polymers for organic solar cells. In addition, the resulting low optical gaps, the promising PCEs with PC₆₁BM as the acceptor, and the good open-circuit voltages (up to 0.8 V) synergistically demonstrate the potential of this class of polymers as donor materials for bottom subcells in organic tandem solar cells.