Synthesis of three new 1‐(2,6‐diisopropylphenyl)‐2,5‐di(2‐thienyl) pyrrole‐based donor polymers and their bulk heterojunction solar cell applications

• Published in: Journal of polymer science. Part A, Polymer chemistry Vol. 48; no. 23; pp. 5514 - 5521
• Main Authors: Tamilavan, Vellaiappillai, Song, Myungkwan, Jin, Sung‐Ho, Hyun, Myung Ho
• Format: Journal Article
• Language: English
• Published: Wiley Subscription Services, Inc., A Wiley Company 01.12.2010
• ISSN: 0887-624X; 1099-0518
• DOI: 10.1002/pola.24360

A series of three new 1‐(2,6‐diisopropylphenyl)‐2,5‐di(2‐thienyl)pyrrole‐based polymers such as poly[1‐(2,6‐diisopropylphenyl)‐2,5‐di(2‐thienyl)pyrrole] (PTPT), poly[1,4‐(2,5‐bis(octyloxy)phenylene)‐alt‐5,5'‐(1‐(2,6‐diisopropylphenyl)‐2,5‐di(2‐thienyl)pyrrole)] (PPTPT), and poly[2,5‐(3‐octylthiophene)‐alt‐5,5'‐(1‐(2,6‐diisopropylphenyl)‐2,5‐di(2‐thienyl)pyrrole)] (PTTPT) were synthesized and characterized. The new polymers were readily soluble in common organic solvents and the thermogravimetric analysis showed that the three polymers are thermally stable with the 5% degradation temperature >379 °C. The absorption maxima of the polymers were 478, 483, and 485 nm in thin film and the optical band gaps calculated from the onset wavelength of the optical absorption were 2.15, 2.20, and 2.13 eV, respectively. Each of the polymers was investigated as an electron donor blending with PC₇₀BM as an electron acceptor in bulk heterojunction (BHJ) solar cells. BHJ solar cells were fabricated in ITO/PEDOT:PSS/polymer:PC₇₀BM/TiOx/Al configurations. The BHJ solar cell with PPTPT:PC₇₀BM (1:5 wt %) showed the power conversion efficiency (PCE) of 1.35% (Jsc = 7.41 mA/cm², Voc = 0.56 V, FF = 33%), measured using AM 1.5G solar simulator at 100 mW/cm² light illumination.