Effect of fluorination of the donor unit on the properties of benzodithiophene-triazole based donor-acceptor systems for polymer solar cells: A computational investigation

Assessing Effects of Different π bridges on Properties of Random Benzodithiophene-thienothiophene Donor and Non-fullerene Acceptor Based Active Layer

“…We would also like to mention here that energies of LUMOs were computed by adding the first excitation energies ( E g 1 ) to the E HOMO . Literature shows that this method of computing LUMO values works better compared to taking LUMO energies from the ground state calculations. ,− …”

“…Among various molecular design strategies, donor and acceptor material selection, side-chain incorporation, halogenation, etc. are usually adopted. ,,− In recent times, random polymers have provided another route for molecular design. Common D–A alternating copolymers have a fixed 1:1 ratio of donors and acceptors.…”

“…But there is still a lack of coherent examination of π bridge insertion on the random copolymers. We have been interested in understanding the effects of modifications of donor copolymer, in particular the BDT based units, on the photophysical properties. , In the present work, we focus on the effect of π bridges in the random binary polymer donors. Our aim is manifold: to examine the effect of insertion of strong and weak electron donor π bridges on the (a) binding energies of polymer donors with non-fullerene acceptor, (b) optoelectronic properties, (c) exciton binding energies, and (d) charge transfer and charge recombination processes.…”

Halogenation of the Side Chains in Donor‐Acceptor Based Small Molecules for Photovoltaic Applications: Energetics and Charge‐Transfer Properties from DFT/TDDFT Studies

“…These structural modifications affect the positions of molecular orbitals and absorption spectra, and result in improved chargetransfer properties and thereby improve the PCEs. [12][13][14][15][16][17][18] In this context, halogenation of the molecular backbone is a very effective strategy for structural modifications of polymeric and SMs donor materials to fine-tune the molecular orbital energy levels. [19][20][21][22][23][24] Among the halogens, fluorine, with the highest electronegativity and a small Van der Waals radius has been the most popular in recent times and in most cases, fluorine substitution has resulted in improved performances of the devices.…”

“…Our group has been interested in understanding the effects of substitutions on the donor units in OSCs. [16,48] Keeping in mind that halogen substitution has a large effect on the optoelectronic and photovoltaic properties as discussed in previous paragraph, we have modified A1, A5 and A9 systems by substituting one hydrogen atom in each thiophene ring on the lateral side chains of the BDT donor unit by either a fluorine or a chlorine or a bromine atom. Hence, each of the above three molecules produce three new molecules and we denote those as A2-A4, A6-A9, and A10-A12, respectively.…”