Halogenated conjugated molecules for ambipolar field-effect transistors and non-fullerene organic solar cells

A series of halogenated conjugated molecules, containing F, Cl, Br and I, were easily prepared via Knoevenagel condensation and applied in field-effect transistors and organic solar cells. Halogenated conjugated materials were found to possess deep frontier energy levels and high crystallinity compared to their non-halogenated analogues, which is due to the strong electronegativity and heavy atom effect of halogens. As a result, halogenated semiconductors provide high electron mobilities up to 1.3 cm(2) V-1 s(-1) in transistors and high efficiencies over 9% in non-fullerene solar cells.