ZnO nanowire based visible-transparent ultraviolet detectors on polymer substrates

Abstract

The fabrication and characterization of fully visible-transparent and flexible ultraviolet (UV) detectors, on polyethylene 2,6-naphthalate (PEN) with active channels of zinc oxide nanowires and ohmic indium tin oxide contacts, are reported and discussed. The fabricated detector has an average transmittance of 80% in the visible spectral range and is most responsive at or below 370 nm, the onset of UV light, with a UV/vis rejection ratio of 1.42 × 103. A five orders of magnitude difference in the photocurrent, between UV illumination and dark conditions, are also observed. The single-sided UV response further shows that the PEN substrate performs well as a UV reflector. The noise analysis on the nanowire UV detector indicates a noise equivalent power and detectivity (D*) of 5.88 × 10−13 WHz−0.5 and 2.13 × 109 cm Hz0.5 W−1, respectively.

Drop‐cast and dye‐sensitized ZnO nanorod‐based visible‐light photodetectors

“…When the violet light was illuminated on the ZnO NRs, it resulted in high photoconduction and the photocurrent was increased by about four orders of magnitude from 2.18 × 10 –9 A to 1.58 × 10 –5 A at the applied bias voltage of 5 V. Indeed, the surface defects of ZnO NRs such as vacancies and interstitials were possibly increased with increasing growth time (the defects can be estimated by means of the photoluminescence results (see Supporting Information, S3), which would yield the visible light absorption. To characterize the fabricated photodetector, the photoconductive gain ( G ) was estimated by G = ( I ph / e )/( P / һν ) 11, where I ph and e are the photocurrent and electron charge, and P , һ , and ν are the optical power, Planck constant, and photon frequency, respectively. Assuming that the photons were illuminated on the ZnO NRs with a cross‐sectional area of ∼10 × 13.3 μm 2 , G was roughly calculated to be ∼3.9 × 10 3 at the applied bias voltage of 5 V, which is of considerable value for 1D ZnO nanostructure‐based visible‐light photodetectors.…”

“…It is well known that the photogenerated electron–hole pairs and desorption of oxygen molecules in 1D ZnO nanostructures contribute to the electron–hole pairs at the surface during UV illumination, which induces a photoconductivity 7–9. Accordingly, many studies have been focused on the fabrication and characterization of 1D ZnO nanostructure‐based UV photodetectors by using the chemical vapor deposition (CVD), vapor–liquid–solid process, and hydrothermal synthesis method 10–12. In order to form semiconductor–metal contacts, however, a somewhat complicated process and accurate control for the connections between the metal electrodes have been required until now.…”

Hybrid Nanostructures for Photodetectors

“…In 2001, Lieber's group demonstrated one of the first examples of an individual InP nanowire‐based photodetector exhibiting highly polarized‐sensitive photoconductivity with a responsivity of 3000 A W –1 . Since then there have been many reports on photodetectors constructed from 1D nanostructures, such as ZnO, SnO 2 , TiO 2 and ZnS etc . Since 1D nanostructures have large surface‐to‐volume ratio, their surfaces would influence the photodetector performance drastically.…”

High performance organic ultraviolet photodetector with efficient electroluminescence realized by a thermally activated delayed fluorescence emitter

“…At À1 V, D* is 1.4 Â 10 12 Jones, which lies within the same level as some inorganic UVPDs. 24 Besides, the device also yields rapid switch response between on and off states when the UV light is turned on and off, respectively. As shown in Figure 2(b), when the device was exposed to UV radiation, its current increased sharply with a rise time of less than 200 ms, which is an estimate limited by the instrument resolution.…”