Oa. Elrashiedy et S. Holdcroft, PHOTOELECTROCHEMICAL PROPERTIES OF POLY(3-ALKYLTHIOPHENE) FILMS IN AQUEOUS-SOLUTION, Journal of physical chemistry, 100(13), 1996, pp. 5481-5484
The photoelectrochemical properties of pi-conjugated poly(3-hexylthiop
hene) films in aqueous solution are presented. Application of potentia
l biases more negative than +0.3 V (SCE) to the polymer film immersed
in an aqueous electrolyte gives rise to a depletion layer at the polym
er/solution interface. Photoexcitation of the polymer leads to photore
duction of water. The photovoltage observed is linearly related to pH
of the solution in accordance with the variation in redox potentials o
f the H+/H-2 couple, indicating the absence of Fermi level pinning. Qu
antum efficiencies are dependent on the pH of the solution, irradiatio
n power, excitation wavelength, and film thickness. The capture cross
section of irradiation was varied by controlling the film thickness. W
ith an irradiation wavelength of 435 nm, >90% of the incident light wa
s absorbed within the first 280 nm. Using this wavelength of incident
light, quantum efficiencies reached a maximum for 220 nm thick films.
Quantum efficiencies decreased with increasing incident power.