Photoaction, temperature and O-2 depletion effects in fullerene photoelectrochemical solar cells

It is demonstrated that higher temperature and C-60 oxygen depletion increa se the photocurrent of fullerene photoelectrochemical solar cells (PEC). Fu llerene/iodide electrolyte PEC consisting of intrinsic single crystal C-60 in either aqueous 3 M KI, 0.01 M I-2, or 0.1 M tetrabutyl ammonium iodide, 0.3 M LiClO4 in acetonitrile solution, drive regenerative photoinduced iodi de oxidation. The photocurrent is increased by an order of magnitude (to 6. 4 mu A/cm(2) under 100 mW/cm(2) illumination) by an increase of the aqueous cell temperature from 24 degrees C to 82 degrees C, A similar order of mag nitude increase in photocurrent is accomplished by O-2 depletion pretreatme nt (24 h at 400 degrees C in Ar) of the C-60 to improve conductivity. Howev er, this latter treatment also irreversibly increases the cell dark current . The spectral action of single crystal C-60 is also probed, through the ge nerated photoelectrochemical current in iodide, ferricyanide and sulfuric e lectrolytes as a function of wavelength. Band edges are observed at 720 nm (1.7 eV) and 560 nm (2.2 eV), and a substantial peak photocurrent response occurs at 395 nm (3.1 eV) and decreases at shorter wavelengths. (C) 1998 El sevier Science B.V. All rights reserved.