Design, Synthesis And Performance Study Of Three-dimensional Perylene Diimide (PDIs) Acceptor Materials

In recent years,organic solar cells,as a new and highly promising renewable clean energy technology,have received extensive attention from researchers at home and abroad.At present,the development of high-performance organic solar cells is of great significance for the realization of new energy sources and the transformation of traditional energy structures.In order to further improve the power conversion efficiency of organic solar cells,it is a feasible way to modify the acceptor materials,optimize the structure of the device and the preparation process.In this paper,we started from the aspect of acceptor materials,mainly using triphenylamine（TPA）as the core and pyran-modified perylene diimides（Py-PDIs）as the end-capping unit to construct two novel A-D-A small molecule acceptors.A bulk heterojunction organic solar cell is prepared in combination with a donor material（PBDB-T）.Novel acceptor materials based on perylene diimides are subjected to ¹H and ¹³C nuclear magnetic resonance（NMR）,ultraviolet absorption spectroscopy（UV-vis）,matrix-assisted laser desorption ionization time-of-flight mass spectrometry,electrochemistry（CV）,differentialscanningcalorimetry（DSC）,and thermogravimetry（TGA）.Other characterization methods have been used to study the properties of chemical structure,optics,thermodynamics and so on.Two kinds of photovoltaic devices PBDB-T:TPA-PDI₂ and PBDB-T:TPA-PDI₃ were tested by external quantum efficiency（EQE）and atomic force microscopy（AFM）to test the photovoltaic performance and morphology of the device.Studies have shown that TPA-PDI₃-based bulk heterojunction organic solar cells achieve 5.84%energy conversion efficiency（PCE）,which exceeds TPA-PDI₂-based devices（1.314%）.The high efficiency of TPA-PDI₃ can be attributed to the complementary absorption spectrum with the donor material（PBDB-T）,balanced carrier transport and favorable morphology.It is also the highest value reported in the literature based on alkynyl-functionalized triphenylamine-based non-fullerene small molecule acceptors.In addition,two novel acceptor materials,TPP-C5-PDI and TPP-C6-PDI,were synthesized with triphenylphosphine as the core and C5-PDIs and C6-PDIs as the end-capping units.