Substituent effects on furan-phenylene copolymer for photovoltaic improvement: A density functional study

Abstract

The structural, electronic and photovoltaic properties of furan-phenylene copolymer ((Fu-co-Ph)4) and its derivatives were evaluated using density functional theory (DFT) and time-dependent density functional theory (TD-DFT). The calculated band gaps of pristine furan and phenylene are in good agreement with the available experimental data. The lower band gap value of 2.72 eV was obtained from –NO2 and –NHCH3 substituents, leading to broader solar absorption range. With respected to the reorganization energy, –OCH3, –NHCH3, –OH, -SCH3, –CH3, –CF3, –NO2, and -F substituted (Fu-co-Ph)4 structures were classified as better electron donor materials. For combination with PC61BM, –NO2, –CN, –CF3 and –F functionalized copolymers demonstrated significantly higher open circuit voltage (Voc) values ranging from 1.07 to 2.10 eV. Our results revealed that electron withdrawing group substitution on furan-phenylene copolymers was an effective way for improving electronic and optical properties of donor materials used in photovoltaic applications.