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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.
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 (ADA) 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.