Designing Benzodithiophene‐Based Donor Materials with Favorable Photovoltaic Parameters for Bulk Heterojunction Organic Solar Cells

Abstract

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).

Impact of halogens on electronic and photovoltaic properties of organic semiconductors: A multiscale computational modeling

“…High exciton bonding energy causes energy losses. [ 36–38 ] We have studied the effect of halogen substituent on terminal group of SMAs. The exciton bonding energy (E b ) can be calculated through below equation: In above equation, HOMO‐LUMO energy gap (∆ H‐L ) is assumed to be equal to the electronic band gap (E g ).…”

“…High exciton bonding energy causes energy losses. [36][37][38] We have studied the effect of halogen substituent on terminal group of SMAs. The exciton bonding energy (E b ) can be calculated through below equation:…”

Metallo-dithiaporphyrin pigments for bulk-heterojunction solar cell applications: ab initio investigation of structural and optoelectronic properties

“…Ionization potential (IP), electron affinity (EA), and reorganization energy (l) are the key parameters that determine the energy barrier for the charge injection process of organic molecules. 37 Electron affinities and vertical ionization potentials have been computed by using eqn (1) and (2). 38 EA = E 0 − E −…”

Theoretical Calculations of the Optical and Electronic Properties of Dithienosilole‐ and Dithiophene‐Based Donor Materials for Organic Solar Cells

“…Furthermore, excitation energy decreased by increasing the electron withdrawing potential of the acceptor atom. Reference molecules R a ‐ R d and designed donor molecules M 1 ‐M 3 and M 4 ‐M 6 exhibited two types of absorption peaks, the shorter wavelength absorption peak is due to the π to π* transition in the main chain molecule, whereas the longer wavelength absorption peak is due to the transfer of charges among the donor and acceptor moiety found in the A−D−A type of designed donor molecule . Furthermore absorption peak in longer wavelength region displayed higher value of intensity whereas shorter wavelength region showed lower intensity of peak (Figure A−D).…”