Highly responsive UV-photodetectors based on single electrospun TiO₂ nanofibres

Abstract

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

Tunable Photodetectors via in Situ Thermal Conversion of TiS₃ to TiO₂

“…While in the first three traces the device responds to all the probed wavelengths from 375 nm to 660 nm, in the last four traces the responsivity shows an abrupt decrease for wavelengths larger than 450 nm, indicating that there is a blue-shift of the cut-off wavelength of the photodetector. The wavelength-resolved responsivity reported in the initial and final stages of the device are compatible with previously reported spectra of TiS3 and TiO2 photodetectors 17,41 . Figure 6b shows the evolution of the responsivity at 405 nm as a function of the incident optical power.…”

Ultraviolet Detectors Based on Wide Bandgap Semiconductor Nanowire: A Review

“…The printed photodetector was highly transparent with a visible transmittance of 85% and showed a low dark current of 10 −12 A with a high on/off ratio of 2000. Under a bias voltage of 2 V, a fast rise time of 0.4 s was achieved, with a recovery time of 0.1 s. Molina-Mendoza et al [ 84 ] presented UV photodetector devices based on individual electro-spun TiO 2 nanofibers transferred onto pre-patterned electrodes. As shown in Figure 10 , the fabricated devices demonstrated an outstanding UV photoresponse of ~90 A/W and a response time of ~5 s.…”

ZnO Film UV Photodetector with Enhanced Performance: Heterojunction with CdMoO4 Microplates and the Hot Electron Injection Effect of Au Nanoparticles

“…High sensitivity, high signal‐to‐noise ratio, high spectral selectivity, high speed, and high stability are required for high performance UV PDs . Selecting appropriate active materials is of great importance for fabricating PDs with high performance …”