Unravelling the photovoltaic response of butterfly-shaped fulvene based chromophores with the influence of double acceptor moieties: A DFT approach

Abstract

Herein, a series of butterfly-shaped fulvene based acceptor molecules (PTMR and PTMD1-PTMD7) with A2-π-A1-π-A2 configuration was designed to explore their photovoltaic behavior. This designing strategy was carried out via incorporating extended end-capped acceptors at the peripherals of conjugated tetraphenyl fulvene core (5nT). Density functional theory (DFT) and time-dependent DFT (TD-DFT) approaches were conducted on the designed compounds to elucidate their structure–property relationships, photovoltaic and opto-electronic characteristics. Various analyses like HOMO-LUMO energy gaps, absorption maxima, density of states, binding energies of electrons and holes, transition density matrix, and open-circuit voltage, were employed to investigate photovoltaic behaviour of the entitled compounds. Interestingly, all the designed molecules (PTMR and PTMD1-PTMD7) exhibited remarkable photovoltaic characteristics, such as minimal bandgap values in range of 2.275–2.310 eV, red-shifted absorption maxima (range 715–722 nm) with good open-circuit voltage values. Moreover, all the derivatives exhibit lower binding energies with a decreasing order of PTMD1 > PTMD2 = PTMD3 > PTMD6 > PTMR > PTMD7 > PTMD5 > PTMD4. Particularly, PTMD4 reveal the smallest exciton binding energy of 0.546 eV. These findings suggest that the entitled newly tetraphenyl fulvene based NFAs specifically PTMD4 hold significant potential as highly efficient candidates in the field of organic solar cells.