Photocurrent increment in organic solar cell with mixed solid of merocyanine and zinc porphyrin

The short-circuit photocurrent in Al/dye/Au sandwich-type cell with a mixed solid of 3-ethyl-5-[(3-ethyl-2(3H)-benzothiazolylidene)ethylidene]-2-thiox o-4-thiazolidinone (MC) and 5,10,15,20-tetraphenylporphyrinatozinc (Zntpp) was much larger than that in the cell with a pure MC solid or a pure Zntpp solid. The maximum photocurrent quantum yields of 7.4% at 440 nm monochroma tic light absorbed mainly by Zntpp and 4.7% at 555 nm monochromatic light a bsorbed by both MC and Zntpp were obtained for the mixed solid cells of R = 0.35 and R = 0.23, respectively, where R indicates the molar ratio of Zntp p to total dye. Since the hole density in the organic solid decreased with mixing Zntpp into R-IC solid, this improvement was not explained by this fa ctor. We believe that a dissociation efficiency of a photoproduced electron -hole pair (exciton) in the mixed solid may have increased because of relat ively large intermolecular interaction between MC and Zntpp molecules. This effect is considered to be responsible for this photocurrent increment. (C ) 1998 Elsevier Science S.A. All rights reserved.