Triplet Sensitizer Modification of Poly(3-hexyl)thiophene (P3HT) for Increased Efficiency in Bulk Heterojunction Photovoltaic Devices

Authors: Punnamchandar Ramidi, Omar Abdulrazzaq, Charlette M. Felton, Yashraj Gartia,Viney Saini, Alexandru S. Biris, and Anindya Ghosh

Publication: Energy Technology, Volume 2, Issue 7

Abstract:

We present the successful synthesis of a modified poly(3-hexyl)thiophene (P3HT) donor polymer with benzophenone (P3HTB) substitution. The triplet-sensitizer (benzophenone)-containing polymer (P3HTB) was synthesized by the oxidative copolymerization of 3-hexylthiophene and benzopheneone-modified thiophene [2-phenyl-2-(4-(thiophen-3-yl)phenyl)-1,3-dioxolane] and deprotecting the cyclic ketal group. The resulting polymer was characterized by using nuclear magnetic resonance spectroscopy (¹H NMR and ¹³C NMR) and Fourier transform infrared spectroscopy (FTIR). Different ratios of the copolymer (P3HTB) and pristine P3HT mixtures were used for the fabrication and characterization of bulk heterojunction (BHJ) cells, with [6,6]-Phenyl C₆₁ butyric acid methyl ester (PCBM) used as the acceptor in fabricating the active layers. An increase in power conversion efficiency (≈15 %) was observed with devices fabricated with 2.5 and 5 wt % P3HTB mixed with P3HT compared to those fabricated with P3HT alone.