Synthesis And Photovoltaic Properties Of Nonfullerene Small Molecule Acceptor

Organic solar cells?OSCs?have shown great potential for commercial application due to light weight,low cost and capability to fabricate large-scale devices.To promote industrialization of organic solar cells,more works have to be done,especially developing materials for OSCs.This paper summarized nonfullerene acceptors in organic solar cells and how they were developed.Besides,one wide-gap acceptor with three-dimensional structure based on perylene diimides,BP-PDI₄ and a narrow-gap acceptors based on pyran,PTIC and were designed synthesized.With a biphenyl core armed with four bulky PDI units,the resulting molecule shows a twisted 3D structure and the intrisic large aggregation of perylene diimides in active layer blends was successfully suppressed.By introducing oxygen atoms into the commonly used indacenodithiophene?IDT?unit,the electron-donating ability of the new donor core was enhanced.In consequence,the absorption spectra of acceptor with ADA structure was broadened and redshifted.In addition,these acceptors and their photovoltaic properties were fully characterized.?1?According to the absorption spectra of BP-PDI₄ and perylene diimide monomer,the aggregation was successfully suppressed,which indicated that constructing 3D structure was an effective method to alleviate the aggregation tendency of acceptors based on perylene diimides.When BP-PDI₄ was blended with PTB7-Th or PBDTTT-C-T,the blend films were homogeneous and smooth.A maximum power conversion efficiency of2.95%was achieved based on BP-PDI₄.?2?With addition of oxygen atoms,the new donor core,PDT has stronger electron-donating ability.Therefore,the intramolecular charge transfer of ADA type acceptor is promoted and the HOMO energy levels are upshifted,as a result of which,these new acceptors obtain narrower bandgap,broadened and redshifted absorption.Combined PTIC with polymer donor PBDB-T,a maxmiun PCE of 7.66%was achieved.