A low bandgap polymer based on isoindigo and bis(dialkylthienyl)benzodithiophene for organic photovoltaic applications. Issue 1 (14th August 2012)

• Record Type: Journal Article
• Authors: Cao, Kangli; Wu, Zhongwei; Li, Shugang; Sun, Baoquan; Zhang, Guobing; Zhang, Qing
• Is Part Of: Journal of polymer science. Volume 51:Issue 1(2013:Jan.)
• Page Start: 94
• Page End: 100
• Publication Date: 2012-08-14
• Subjects: 547
• DOI: 10.1002/pola.26275
• Languages: English
• ISSNs: 0887-624X

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>A new conjugated polymer <bold>PBDTT‐ID</bold> based on <italic>N</italic>‐alkylated isoindigo (ID) and bis(2, 3‐dialkylthienyl)‐substituted benzo[1, 2‐<italic>b</italic>:4, 5‐<italic>b′</italic>]dithiophene (BDTT) as repeating units was synthesized. It had an optical bandgap of 1.56 eV and a highest occupied molecular orbital (HOMO) energy level of −5.71 eV. The optical, electrochemical, and photovoltaic properties of new polymer were compared with previous reported polymer <bold>PBDT‐ID</bold>, which was based on bis(alkoxy)‐substituted benzo[1, 2‐<italic>b</italic>:4, 5‐<italic>b′</italic>]dithiophene. The new polymer displayed lower HOMO energy level and better absorption properties than polymer <bold>PBDT‐ID</bold>. The solar cells fabricated with <bold>PBDTT‐ID</bold>/PC<sub>61</sub>BM (1:2, <italic>w/w</italic>) blends as active layers exhibited photoresponse in the range of 300–800 nm. A power conversion efficiency of 4.02% and an open circuit voltage (<italic>V</italic><sub>oc</sub>) of 0.94 V were achieved in polymer solar cell device based on the new polymer. This was the highest <italic>V</italic><sub>oc</sub> realized among the isoindigo‐based polymers. The relatively high performances of new polymer in solar cell devices were interpreted in terms of material properties and morphologies of polymer/PCBM blends. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013</p> </abstract>