Design and analysis of benzene fused conjugated molecules for organic Photovoltaics: A TD-DFT study on electronic and quantum chemical properties

In this work, fifteen different benzene fused conjugated molecules were designed and analyzed by comparing their properties using TD-DFT (time dependent density functional theory) with a basic set of B3LYP/6-311G(d,p) for organic photovoltaics. The core molecules used were benzodioxazole, benzodioxole, benzodithiazole, benzofurazan and benzotriazole. Optimized geometry and electronic properties such as HOMO, LUMO, band gap and quantum chemical parameters were determined. Predicted band gap ranges from 1.6 to 3.8 eV. Some compounds have a good absorption property (above 500 nm) which is suitable for our purpose. The study assists in the identification of materials with advantageous electrical, optical and photovoltaic characteristics that can serve as donor molecules in heterojunction organic solar cells. The theoretical studies also aided in the clarification of the structure-property relationships that significantly affect efficiency of the device.