It is demonstrated that higher temperature and C60 oxygen depletion increase the photocurrent of fullerene photoelectrochemical solar cells (PEC). Fullerene/iodide electrolyte PEC consisting of intrinsic single crystal C60 in either aqueous 3 M KI, 0.01 M I2, or 0.1 M tetrabutyl ammonium iodide, 0.3 M LiClO4 in acetonitrile solution, drive regenerative photoinduced iodide oxidation. The photocurrent is increased by an order of magnitude (to 6.4 μA/cm2 under 100 mW/cm2 illumination) by an increase of the aqueous cell temperature from 24°C to 82°C. A similar order of magnitude increase in photocurrent is accomplished by O2 depletion pretreatment (24 h at 400°C in Ar) of the C60 to improve conductivity. However, this latter treatment also irreversibly increases the cell dark current. The spectral action of single crystal C60 is also probed, through the generated photoelectrochemical current in iodide, ferricyanide and sulfuric electrolytes 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.
- Depletion effects