Chemical Design Rules for Non?Fullerene Acceptors in Organic Solar Cells

Efficiencies of organic solar cells have practically doubled since the development non-fullerene acceptors (NFAs). However, generic chemical design rules for donor-NFA combinations are still needed. Such proposed by analyzing inhomogeneous electrostatic fields at donor–acceptor interface. It is shown that an acceptor–donor–acceptor molecular architecture, and alignment parallel to interface, results in energy level bending destabilizes charge transfer state, thus promoting its dissociation into free charges. By a series PCE10:NFA cells, with NFAs including Y6, IEICO, ITIC, as well their halogenated derivatives, it suggested quadrupole moment ?75 Debye Å balances losses open circuit voltage gains generation efficiency.