Tuning molecular energy levels of dyes for bulk heterojunction solar cells

Concerning the synthesis of donor molecules with intended energy levels suitable for high efficiency bulk heterojunction solar cells, we rationally designed a series of diketopyrrolopyrrole-benzothiadiazoles based donor material. The efficiency of the final solar cells was evaluated by a mathematical model implementing electronic properties of molecules by density functional theory approach. Consequently a designed oligomer dye structure obtained with up to 9.1 percent in a bulk heterojunction efficiency solar cell system.