Computational Study of New Small Molecules based Thiophene as Donor Materials for Bulk Heterojunction Photovoltaic Cells.

In this research work, we study the structural, optical, electronic, and photovoltaic properties of eight thiophene-based π-conjugated organic molecules using quantum methods namely time-dependent density functional theory. In particular, we identify the relationships between the chemical structure of these π-conjugated organic molecules and their optoelectronic properties. Moreover, we calculate and compare the highest energy occupied molecular orbital and lowest energy unoccupied molecular orbital energy levels of these compounds which act as donor with the ones of the acceptorphenyl-C-butyric acid methyl ester. As a result, the investigated molecules show a low band gap, suitable open-circuit voltage and appropriate alignment energy level between the engineered donor molecules and the acceptor phenyl-C-butyric acid methyl ester. This theoretical study shows that these new molecules have potential properties for the development of organic heterojunction photovoltaic cells.