| Summary: | 碩士 === 國立交通大學 === 應用化學系碩博士班 === 107 === Organic Solar Cells (OSCs) have attracted much more interests over past few decades. The commonly-used fullerene derivatives have their drawbacks such as morphological instability, high costs, and poor absorption. To overcome these issues, we designed and synthesized a series of novel n-type small molecule using octacyclic ladder-type naphthodi(cyclopentadithiophene) (NDCPDT) as central core end-capped with different electron withdrawing moieties to furnish A-D-A type non-fullerene acceptors NCIC and NCFIC. With easier synthesis, broader absorption spectra and tunable energy level, NCIC and NCFIC were blended with p-type polymer PBDB-T to obtain binary device with efficiency of 7.31% and 7.52%, respectively. The better performance of NCFIC blends than that of NCIC is attributed to introducing a stronger electron withdrawing moiety which leads to better intramolecular charge transfer. We also selected polymer J71 for enhanced Voc；as a result, NCFIC:J71 got even higher efficiency of 8.78%. Ternary-blend device with an additional acceptor, PC71BM, was further obtained for gradient energy alignments and more efficient light harvesting. These ternary blends using PBDB-T:NCIC:PC71BM (1:1:1 in wt%) and PBDB-T:NCFIC:PC71BM (1:1:1.5 in wt%) achieved improved PCE of 8.32% and 9.18%.
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