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Six Acceptor‐Donor‐Acceptor (A−D−A) types molecules with dimethyl dithieno[3, 2‐b:2′,3′‐d]silole)−2,6‐diyl (DTS) (M1‐M3) and dimethyl cyclopenta [2, 1‐b;3,4‐b]‐dithiophene (CPDT) (M4‐M6) core flanged by different acceptor units through methylthiophene bridge are evaluated as donor materials for photovoltaic applications. The photovoltaic properties of M1‐M3 and M4‐M6 are compared with standard RaRc and Rb,Rd respectively. Geometry optimization was performed with CAM−B3LYP/6‐31G (d) level of theory. TD‐CAM−B3LYP has been employed for the estimation of excited state properties of the molecules. M1, M2, M3 and M4, M5, M6 symbolized suitable frontier molecular orbital's (FMO's) energy levels with broad absorption spectra. The electron withdrawing substituents impart red shift in absorption spectra along with good consistancy of designed donor molecules. Reorganization energies of donor molecules (M1‐M6) showed ideal properties of charge mobility. M1 and M4 illustrated lowest λe values as compared to λh, thus dictated that designed donor molecules are of good choice for their electron donating ability. Furthermore, M2 and M6 demonstrated shortest Eg of 3.7 and 3.72 eV among HOMO and LUMO energy levels.

Computational study on four Acceptor‐Donor‐Acceptor (A–D‐A) type of donor molecules namely, dimethyl cyanoacetate terthiophene di(methylthiophene) benzo[1,2‐b:4,5‐b′]dithiophene (DMCATDMTBDT) (M1), methylrhodanine terthiophene di (methylthiophene) benzo[1,2‐b:4,5‐b′]dithiophene (MRTDMTBDT) (M2), dimethyl cyanoacetate terthiophene di (fluoromethyl thiophene) benzo[1,2‐b:4,5‐b′]dithiophene (DMCATDFMTBDT) (M3), and methylrhodanine terthiophene di (fluoromethyl thiophene) benzo[1,2‐b:4,5‐b′]dithiophene (MRTDFMTBDT) (M4) was carried out and their photovoltaic properties were associated with methyl cyanoacetate terthiophene di (methoxy) benzo[1,2‐b:4,5‐b′]dithiophene (DCAO3TBDT) (R1) and methylrhodanine terthiophene di (methoxy) benzo[1,2‐b:4,5‐b′]dithiophene (DR3TBDT) (R2). For the geometry optimization DFT functional CAM−B3LYP/6‐31G (d) was found to be the best choice, hence TD‐CAM−B3LYP/6‐31G (d) was opted for the calculation of excited state of the molecules. M3 and M4 represented appropriate frontier molecular orbital energy levels and broad absorption band. The reorganization energies of the designed molecules illustrated excellent charge mobility property. The lower λe values as compared to λh illustrate that the designed donor molecules are better electron donors. M4 was found as champion molecules with the lowest λe (0.01601) value. The Voc value of M3 and M4 are 2.74 eV and 2.63 eV respectively with respect to the energy levels of PC60BM (acceptor).

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