Molecular designing of high-performance 3D star-shaped electron acceptors containing a truxene core for nonfullerene organic solar cells

End-capped modification is a convenient strategy to enhance the photovoltaic and electronic properties of fullerene-free acceptor materials. In this report, five novel star-shaped three-dimensional acceptor moleculesFH1-FH5are designed by end-capped modifications of recently synthesized star-shaped Tr (Hex)(6)-3BR molecule. The enhancement in the photovoltaic, electronic, and photophysical properties of designed molecules is examined with the aid of density functional theory (DFT) and time-dependent DFT (TDDFT). The MPW1PW91 functional in conjunction with 6-31G(d,p) basis set of DFT/TDDFT is employed in order to compute various key parameters including frontier molecular orbitals analysis, absorption maxima, and binding energy along with transition density matrix, open-circuit voltage, excitation energy, charge mobilities (electron and hole reorganizational energies), density of states, charge transfer with respect to HOMOPTB7-Th-LUMOacceptor, and dipole moment. Red shifting in absorption spectra of acceptor materials is the most important reason for increasing efficiency of organic solar cells. A red shift in absorption spectra of all designed molecules is noted with low excitation energy. Designed moleculesFH1-FH5exhibit narrow energy gap with high electron mobility as compared with Tr (Hex)(6)-3BR molecule. Among all designed molecules,FH4is proved to be the best candidate for fullerene free organic solar cells because of narrow band gap, high charge mobility, high dipole moment, low excitation, and binding energy along with a red shift in absorption spectrum. Moreover, all designed molecules offer high current charge density as compared with Tr (Hex)(6)-3BR. These results indicate that all star-shaped conceptual molecules (FH1-FH5) are ideal aspirants for construction of future organic solar cells.

Automated summary

End-capped modification was used to design five novel star-shaped three-dimensional acceptor molecules, which showed enhanced photovoltaic, electronic, and photophysical properties through density functional theory (DFT) and time-dependent DFT (TDDFT) analysis. The designed molecules exhibited advantages such as red shifting in absorption spectra.