Wavelength-tunable photoconductivity of dye-sensitized TiO2 nanoparticle films.

We report in this Letter that wavelength-tunable photodetectors (PDs) can be fabricated by dye-sensitized TiO2 nanoparticle film. The photoelectric response of the detectors is fast. The photocurrent intensity strongly depends on the absorption wavelength of the dye; thus the on/off ratio as a function of light wavelength can be tuned by absorbing different dye molecules. The corresponding mechanism is also discussed. The principle reported in this Letter can be used to fabricate full spectrum PDs with distinctive wavelength selectivity.