A-D-A small molecule donors based on pyrene and diketopyrrolopyrrole for organic solar cells

Three new electron donating small molecules(SMs),Pyr(EH-DPP)_2,Pyr(HD-DPP)_2 and PyrA(EH-DPP)_2,are designed and synthesized through coupling electron rich pyrene core with electron deficient diketopyrrolopyrrole(DPP) terminals,of which the derived organic solar cells(OSCs) exhibit interesting structure-performance correlation.It shows that the tune of their solubilizing side chains and π-bridge for the acceptor-donor-acceptor(A-D-A) SMs can significantly alter the resultant short-circuit current density and power conversion efficiency(PCE) in OSCs.The Pyr(EH-DPP)_2 with short side chains displays broader absorption and higher hole mobility than the Pyr(HD-DPP)_2 with long side chains.Although showing planar structure,the acetylene bridge-incorporated PyrA(EH-DPP)_2 adapts an undesired edge-on packing and strong aggregation in film,leading to non-ideal morphology and poor miscibility with fullerene acceptors.As a result,the PCE of the solar cell based on Pyr(EH-DPP)_2 is several times higher than those based on Pyr(HD-DPP)_2 and PyrA(EH-DPP)_2,indicating the A-D-A combination of polyaromatics with DPP would be the promising skeleton for developing photovoltaic semiconductors.

Three new electron donating small molecules （SMs）, Pyr（EH-DPP）2, Pyr（HD-DPP）2 and PyrA（EH-DPP）2, are designed and synthesized through coupling electron rich pyrene core with electron deficient diketopyrrolopyrrole （DPP） terminals, of which the derived organic solar cells （OSCs） exhibit interesting structure-performance correlation. It shows that the tune of their solubilizing side chains and n-bridge for the acceptor-donor-acceptor （A-D-A） SMs can significantly alter the resultant short-circuit current density and power conversion efficiency （PCE） in OSCs. The Pyr（EH-DPP）2 with short side chains displays broader absorption and higher hole mobility than the Pyr（HD-DPP）2 with long side chains. Although showing planar structure, the acetylene bridge-incorporated PyrA（EH-DPP）2 adapts an undesired edge-on packing and strong aggregation in film, leading to non-ideal morphology and poor miscibility with fullerene acceptors. As a result, the PCE of the solar cell based on Pyr（EH-DPP）2 is several times higher than those based on Pyr（HD-DPP）： and PyrA（EH-DPP）2, indicating the A-D-A combination of polyaromatics with DPP would be the promising skeleton for developing photovoltaic semiconductors.