Abstract
In the quest to enhance photovoltaic devices' efficiency and swift progress in the organic solar cell, community scientists are focusing on small molecules donors. The four specific donor molecules, namely TDMDN1, TDMDN2, TDMDN3, and TDMDN4, are designed from recently reported synthetic TDMDN reference molecules. The designed molecules TDMDN1-TDMDN4 have phenyl-di-p-tolyl-amine attached with different acceptors (terminal side). Quantum chemical and photovoltaic parameters of TDMDN1-TDMDN4 were estimated through DFT at MPW1PW91/6-31 G+ (d,p) . The parameters that affect the photophysical properties, exciton dynamics, chemical reactivity, and charge mobility of TDMDN1-TDMDN4 were described by calculating absorption profile, transition density matrix, frontier molecular orbit, and density of state, respectively. The result of all analyses demonstrates that TDMDN1-TDMDN4 proved more competent in executing the parameters mentioned above than TDMDN. Among all designed donors, TDMDN4 is recognized as an appropriate material for photovoltaic application due to its encouraging parameters involving reduced HOMO-LUMO energy gap (1.79 eV), lowest transition energy (1.50 eV), and highest lambda(max) value with chloroform (826 nm). The binding energy of TDMDN4 (0.29 eV) has a low value compared to the TDMDN (0.35 eV). In addition, a complex of TDMDN4 with PC61BM further verifies suitable combination. All designed donor molecules are highly recommended to attain suitable photophysical properties in solar cells and thus are proposed for the elite performance of small molecular solar cell devices.