Designing of small molecule non-fullerene acceptors with cyanobenzene core for photovoltaic application

A quantum chemical analysis of four star-shaped anisotropic acceptor molecules (A1-A4) having acceptoracceptor?-acceptor (A-A?-A) architecture has been performed for solar cell applications. The designed acceptors consist of cyano benzene as central core, thiophene as ?-bridge and 2-methylenemalononitrile (A1), 6-methylene-2-thioxo-1,3-thiazinan-4-one (A2), 2-(2-methylene-3-oxo-2,3-dihydro-1H-inden-1ylidene) malononitrile (A3) and 5-methylene-2-thioxothiazolidin-4-one (A4) as peripheral acceptor units. DFT and TD-DFT calculations were performed using selected MPW1PW91 to assess optical, electronic and charge transfer properties of acceptors (A1-A4) which were further characterized through frontier molecular orbitals (FMOs), DOS, reorganization energies, TDM and open-circuit voltage analysis. The results dictated that the substitution of different acceptor units on the three sides of cyano benzene core forming star-shaped molecules can fine tune the FMO energies, absorption properties (between 470 and 524 nm), band gap energies and reorganization energies in accordance with R. Among all acceptors, A3 exhibited exclusively high absorption value (524 nm), lowest band gap (2.46 eV) and lowest hole reorganization energy (0.0037 eV). Moreover, the acceptor molecules have comparable values of open-circuit voltage to R making them quite suitable for photovoltaic applications in OSCs. The electron-deficient core-based acceptors, in this study, open a new door for designing high-performance OSC acceptors.

Automated summary

A quantum chemical analysis was conducted on four star-shaped anisotropic acceptor molecules for solar cell applications, revealing that substituting different acceptor units on the three sides of the central core can fine-tune the energy levels, absorption properties, and band gap energies of the acceptors. Among them, the A3 acceptor showed high absorption, low band gap, and low reorganization energy, making it promising for organic solar cell applications.