Novel donor-acceptor non-fullerene metal-organic solar cells: A first DFT and TD-DFT study

Recently, a multitude number of studies have paid attention to organic solar cells due to their advantages such as flexibility, long life and low cost. In this research, a Donor-Acceptor (D-A) system using dipyrido[3,2-a:2′,3′-c]phenazine (A) as an acceptor and α-sexithiophene (D) as a donor are designed using DFT and TDDFT computational methods. The effect of acceptor complex of Mg, Ca, and Be on the system function is investigated. The complexation of dipyrido[3,2-a:2′,3′-c]phenazine with Mg, Ca, and Be has reduced its orbital energy level. In addition, this complexation has a relatively good performance as A for the introduced D-A system. Computations at the ground state by investigating HOMO&LUMO orbital energy and electron density have been done. This indicates the efficiency of acceptor complex of Ca, which has an energy gap of 0.92 eV, after optimal function of Mg acceptor. The Charge Transfer (CT) at excited state for different acceptors in D-A system is explained by using electron-hole theory and computations. CT results demonstrates that the best function is related to the Ca-acceptor complex, which has the greatest amount of CT with a length of 17.82 Å.