Thiophene vs thiazole: Effect of the π-connector on the properties of phthalimide end-capped diketopyrrolopyrrole based molecular acceptors for organic photovoltaics

Two phthalimide end-capped diketopyrrolopyrrole based non-fullerene derivatives distinguished by the nature of the π-conjugated connector namely a thiophene or a thiazole ring were synthesized via direct arylation and evaluated as electron acceptor materials in air-processed inverted organic solar cells. It turns out that this simple chemical modification significantly impacts the energetics, the charge transport properties and consequently the photovoltaic performances.