In this work we study the optoelectronic properties of individual TiO2 fibresproduced through coupled sol-gel and electrospinning, by depositing them ontopre-patterned Ti/Au electrodes on SiO2/Si substrates. Transport measurements inthe dark give a conductivity above 2*10^-5 S, which increases up to 8*10^-5 Sin vacuum. Photocurrent measurements under UV-irradiation show high sensitivity(responsivity of 90 A/W for 375 nm wavelength) and a response time toillumination of ~ 5 s, which is superior to state-of-the-art TiO2-based UVphotodetectors. Both responsivity and response speed are higher in air than invacuum, due to oxygen adsorbed on the TiO2 surface which traps photoexcitedfree electrons in the conduction band, thus reducing the recombinationprocesses. The photodetectors are sensitive to light polarization, with ananisotropy ratio of 12%. These results highlight the interesting combination oflarge surface area and low 1D transport resistance in electrospun TiO2 fibres.The simplicity of the sol-gel/electrospinning synthesis method, combined with afast response and high responsivity makes them attractive candidates forUV-photodetection in ambient conditions. We anticipate their high (photo)conductance is also relevant for photocatalysis and dye-sensitized solar cells.
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