A recently synthesized photoactive donor named uorinated thienyl substituted benzodithiophene (DRTB-FT), modi ed with four novel end capped acceptor molecules, have been investigated through different electrical, quantum and spectrochemical techniques for their enhanced electro-optical and photovoltaic properties. DRTB-FT was connected to 2-methylenemalononitrile (D-1), 2-methylene-3-oxobutanenitrile (D-2), 2-(2-methylene-3-oxo-2,3-dihydro-1H-inden-1-ylidene) malonitrile (D-3) and 3-methyl-5methylene-2thioxothiazolidin-4-one (D-4) as terminal acceptor moieties. The architectural D-1 and D-3 molecules owe reduced optical band gap of 2.45 and 2.28 eV bene ted from A-D-A con guration and have broaden maximum absorption band (λ max ) at 617 and 602 nm in polar organic solvent (chloroform). Reduced optical band gap set the ease for enhanced absorption. Reorganization energy of electron (λ e ) of D-3 molecule (0.00397 eV) was smaller amongst all which disclosed its greater mobility of conducting electrons (ICT). Larger values of dipole moment (µ) of D-1(5.939 Debye) and D-3 (3.661 Debye) molecules in comparison to R indicated greater solubilities of the targeted molecules. Among the tailored molecules, D-3 showed lowest binding energy of 0.25 eV in solvent phase and 0.08 eV in gaseous phase.The voltaic strength of designed molecules was examined with respect to fullerene derivative (PC 61 BM) which exposed that D-1 is the best choice for achieving higher PCE. TDM (transition density matrix), DOS (density of states) analysis and binding energies all were estimated at MPW1PW91/6-31G (d, p) level of DFT (density functional theory).

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In this paper, four small molecules B1, B2, B3 and B4 based on donor–acceptor–donor–acceptor–donor (D-A-D-A-D) combination were designed by making structural modifications in R. The designed molecules contain 5,10-dihydro-indolo [3,2-b] indole central donor core and different benzo-thiadiazole and fluorine substituted benzothiadiazole (FBT) acceptor units. These molecules have different subunits introduced on 5,10-dihydroindolo [3,2-b] indole central core like benzo [1,2,5] thiadiazole in (B1), 5-Fluoro-benzo [1,2,5] thiadiazole in (B2), 5-Methyl-benzo [1,2,5] thiadiazole in (B3), 2-Fluoro-2-methyl-2-H-benzotriazole unit in (B4), flanked with [2,2’,5’,2”] terthiophene as spacer (S) and triphenyl amine as a common end-capped donor in all the molecules (B1–B4). The optoelectronic properties of these molecules were studied by performing density functional theory (DFT) at CAM-B3LYP. Among all the designed structures, B2 showed maximum absorption (457[Formula: see text]nm) due to its strong electron withdrawing 5-Fluoro-benzo [1,2,5] thiadiazole acceptor unit. Other opto-electronic properties were analyzed through reorganization energies, density of electronic states and transition density matrix (TDM) to estimate the photovoltaic potential of these newly designed molecules. Low exciton binding energies and comparable values of open circuit voltage than R indicate the worth of these candidates to be used in future solar energy driven devices.

A recently synthesized photoactive donor named fluorinated thienyl substituted benzodithiophene (DRTB-FT), modified with four novel end capped acceptor molecules, have been investigated through different electrical, quantum and spectrochemical techniques for their enhanced electro-optical and photovoltaic properties. DRTB-FT was connected to 2-methylenemalononitrile (D-1), 2-methylene-3-oxobutanenitrile (D-2), 2-(2-methylene-3-oxo-2,3-dihydro-1H-inden-1-ylidene) malonitrile (D-3) and 3-methyl-5methylene-2-thioxothiazolidin-4-one (D-4) as terminal acceptor moieties. The architectural D-1 and D-3 molecules owe reduced optical band gap of 2.45 and 2.28 eV benefited from A-D-A configuration and have broaden maximum absorption band (λmax) at 617 and 602 nm in polar organic solvent (chloroform). Reduced optical band gap set the ease for enhanced absorption. Reorganization energy of electron (λe) of D-3 molecule (0.00397 eV) was smaller amongst all which disclosed its greater mobility of conducting electrons (ICT). Larger values of dipole moment (µ) of D-1(5.939 Debye) and D-3 (3.661 Debye) molecules in comparison to R indicated greater solubilities of the targeted molecules. Among the tailored molecules, D-3 showed lowest binding energy of 0.25 eV in solvent phase and 0.08 eV in gaseous phase. The voltaic strength of designed molecules was examined with respect to fullerene derivative (PC61BM) which exposed that D-1 is the best choice for achieving higher PCE. TDM (transition density matrix), DOS (density of states) analysis and binding energies all were estimated at MPW1PW91/6-31G (d, p) level of DFT (density functional theory).