Synthesis And Photovoltaic Properties Of Organic Photovoltaic Materials Consisting Of Diketopyrrolopyrrole And Thieno[3,2-b]thiophene

Energy has been a critical factor in the development of human society. Due to the increasing energy requirements and non-renewability of fossil energy, people have to look for and develop new sources of energy. Solar for its clean, renewable and other characteristics has been widespread concern in the community. In recent years, organic photovoltaics(OPV) have made some encouraging progress, the bulk heterojunction polymer solar cells(BHJ PSCs) have the energy conversion efficiency(PCE) of over 10%, the maximum PCE of dye-sensitized solar cells(DSSCs) has reached 13%. However, before achieving the commercial application, there are still many difficulties and obstacles. In such a background, we designed and synthesized two donor materials of polymers which were based on pyrrole-dione(DPP) in the main chain, as well as two small organic dyes. The intermediates and target products were characterized by NMR, TOF mass spectrometry test methods. And photophysical and electrochemical properties of the target polymers and organic dye molecules were researched. We have fabricated BHJ PSCs based on the target polymer and DSSCs based on the target dye, their photovoltaic performances were tested simultaneously. The main contents of this paper are as follows:1. Two conjugated copolymers SP3 and SP5 based on diketopyrrolopyrrole(DPP) and BDTT(or TBT) were synthesized. We tested their photophysical, electrochemical and photovoltaic properties. The results showed that hexyl onto two thiophenes connected with DPP, can enhance the solubility of the copolymers to some extent, and adjust the shape of the active layers. Wherein, SP3 had better molecular packing in the solid film resulting a broader absorption spectrum(compared with SP5), while the active layers exhibited better flatness and micro-phase separation. So PSCs based on SP3/PC61 BM have a higher short-circuit current and fill factor. The energy conversion efficiency of polymer solar cells device based on SP3/PC61 BM was 3.51% greater than SP5 of 2.46%.2. We designed and synthesized two D-π-A type organic dyes SD1 and SD2 containing triphenylamine(TPA) and thieno[3,2-b]thiophene(TT). The only difference between the two dyes was the different locations of a methyl on the TT unit. UV-visible absorption spectroscopy, electrochemical and photovoltaic properties of the two dyes were tested and compared. We found that SD2 with the mehtyl attached to the side nearby cyanoacetate group obtained better PCE, due to its lower recombination rate. Under simulated sunlight AM1.5, PCE of DSSCs based on SD1 was 4.02%, while the SD2 attained a higher 6.00%.