Tuning the Optoelectronic Properties of Naphtho-Dithiophene-Based A-D-A Type Small Donor Molecules for Bulk Hetero-Junction Organic Solar Cells

摘要

Four acceptor-donor-acceptor (A-D-A) type small molecules using naphtho-dithiophene as central building block, trithiophene as p-bridges, malononitrile and 2-Thioxo-thiazolidin-4- one as end acceptor groups were designed by using density functional theory (DFT) and investigated as donor materials for organic solar cells (OSCs). The effects of end acceptor groups on absorption, charge transport, morphology, energy level and photovoltaic properties of the molecules were investigated and compared with reference molecule (R1= NDTP-CNCOO). These designed molecules showed relatively low HOMO levels of -5.46 to -5.56 eV, strong absorption between 440–650 nm by using chloroform as solvent. The designed donor molecules have an excellent electron mobility from 0.0161 to 0.0201 V, hole mobility from 0.0275 to 0.0307 V and open circuit voltage (Voc) from 1.76 to 1.86 V. This study revealed that the designed donor materials are suitable and recommended for high performance organic solar cell devices.