Interaction between the Non-Fullerene Acceptor ITIC and Potassium

Abstract

Using density functional theory calculations and photoemission measurements, we have studied the interaction between the non-fullerene small-molecule acceptor ITIC and K atoms (a representative of reactive metals). It is found that the acceptor–donor–acceptor-type geometric structure and the electronic structure of ITIC largely decide the interaction process. One ITIC molecule can combine with more than 20 K atoms. For stoichiometries K x ≤6 ITIC, the K atoms are attracted to the acceptor units of the molecule and donate their 4s electrons to the unoccupied molecular orbitals. K–ITIC organometallic complexes, characterized by the breaking of some S–C bonds in the donor unit of ITIC and the formation of K–S bonds, are formed for stoichiometries K x ≥7 ITIC. The complexes are still conjugated despite the breaking of some S–C bonds.

The effect of solvent on determining highest occupied molecular orbital energies of semiconducting organic molecules: Insight from a combined computational approach

“…Theoretical modeling can assist in interpretation of E HOMO values from electrochemical measurements. Although first principles density functional theory (DFT) methods are well-established to compute the energy levels of organic materials such as ambipolar diketopyrrolopyrrole oligomers, 23 polymer donors, 24 and non-fullerene acceptors, 25 the effect of solvent was not considered. To model solvation within DFT, there are two approaches: the implicit model has the solute immersed in a dielectric continuum (the solvent), versus explicit solvation in which the solute and solvent molecules are treated as discrete entities.…”