Novel A-π-D-π-A-type Non-Fullerene Acceptors for Solution-Processed Organic Photovoltaic Cells: A DFT Study

For the evaluation of the effectiveness of an experimental molecule, it must first be prepared, which is quite expensive if you have to test several such molecules. For this purpose, computational studies and many computer-based softwares are being utilized, to save time as well as resources, and to eliminate the molecules that show reduced efficiency even on the computational scale. With this in mind, we have computationally designed five new acceptor molecules (IC1-IC5) of A-π-D-π-A configuration, through the substitution of significant acceptor moieties in the indacenodithiophene donor core of the ICR molecule, along with the insertion of thiophene π-linkers between the core and the newly introduced acceptors. By using density functional theory (DFT) calculations at the B3LYP/6-31G(d,p), optoelectronic characteristics of IC1-IC5 molecules at their excited and ground state were studied theoretically and contrasted to the reference molecule ICR. As opposed to ICR, all modified molecules possessed redshift in their λmax in both gaseous and solvent (dichloromethane) phases. They also exhibited smaller bandgaps, lower excitation energies, and greater oscillator strength than ICR molecule. Moreover, when compared with ICR, all the new computationally designed molecules, except IC1, had better light-harvesting efficiency. The smaller reorganization energy values for electron mobility of all the newly developed molecules demonstrated their enhanced capabilities as electron carriers. Upon the calculation of photovoltaic attributes of ICR, IC1-IC5 acceptors regarding PTB7-Th donor, the IC3 and IC4 molecules exhibited greater open-circuit voltage (VOC), normalized VOC, and fill factor than ICR molecule, making them more efficient acceptors than the previously reported reference molecule. Thus in the future, both these molecules could be utilized for the anticipation of the enhancement in the solar efficiency of various organic photovoltaic devices.