Abstract
Currently, organic solar cells (OSCs) with non-fullerene electron acceptors offer the highest efficiencies among all reported OSCs. To further improve the efficiencies and stabilities of fullerene-free organic solar cells, end-capped acceptor variations is built with strong electron withdrawing groups. In this report, we have theoretically calculated five new butterfly-shaped fullerene-free acceptors (FD1-FD6) by making end-capped modifications on reference molecule (R) with the purpose to study the improvement in photophysical, opto-electronic, and photo-voltaic properties of newly designed molecules by employing density functional theory (DFT) and time dependent (TD-DFT). Besides, some properties like position of frontier molecular orbitals (FMOs), excitation and binding energy, hole-electron overlap, density of states, overlap density of states, molecular electrostatic potential, open circuit voltage, transition density matrix, and reorganizational energy of electron and hole are also considered and associated with experimentally synthesized reference compound. All calculated molecules displayed a good red-shifting with high charge mobility of electrons among low binding and excitation energies as opposed to reference molecule. Furthermore, all designed molecules (FD1-FD6) and the reference R shows narrow band-gap along-with great charge shifting capability. This theoretical framework proves that end-capped acceptors variation is a modest and effective strategy to accomplish the desirable opto-electronic properties. Therefore, FD1-FD6 are suggested to experimentalist for out-looking future developments to fabricate highly efficient solar cells devices.
Transition density of states (TDOS) of the Si(100)2 × 1 surface derived from the L2,3VV Auger lineshape compared with cluster calculations
