Fabrication and Characterization of a Capacitive Photodetector Comprising a ZnS/Cu Particle/Poly(vinyl butyral) Composite

Abstract

Most photodetectors developed to date essentially measure photocurrents induced by the generation and separation of electron−hole pairs in semiconductors during irradiation. Although the above light detection method is well established, highly sensitive, and applicable to a broad range of semiconductor materials, it requires the presence of a stable and direct contact between the semiconductor and the electrode for accurate photocurrent measurements. In turn, this prerequisite necessitates the use of various costly processes for device fabrication (e.g., photolithography and vacuum deposition of semiconductors/metals) and complicates the development of flexible devices. Herein, inspired by the fact that the dielectric properties of certain materials can be changed by light irradiation, we dispersed ZnS/Cu semiconducting particles in poly(vinyl butyral) to prepare a free-standing composite film and formed two layers of Ag nanowire electrodes on both sides of the cured composite to fabricate a photodetector of a completely new type. The developed device exhibited a capacitance very sensitive to irradiation with light of a specific wavelength and additionally featured the advantages of simple structure/operation mechanism, mechanical flexibility, and transparency, not showing any signs of performance deterioration even after severe damage.

Highly Stabilized Flexible Transparent Capacitive Photodetector Based on Silver Nanowire/Graphene Hybrid Electrodes

“…The band gap of ZnS:Cu particles was calculated based on the Tauc plot equation, the details of which are described in our previous study. 31 As mentioned earlier, as the thickness of the electrodes increases, the overall device transmittance decreases, and the sensitivity decreases. This is because as the thickness of the electrode increases, the light transmitted through the ZnS:Cu-PVB composite lm decreases, and the amount of charge to be transferred decreases.…”

“…To investigate the chemical stability, pH solutions were prepared by mixing a solution of hydrochloric acid (HCl) and sodium hydroxide (NaOH) with deionized water 23 . An inductancecapacitance-resistance (LCR) meter (HP4284A, Agilent) was used to measure the sample capacitance upon light irradiation 31 The increase in the dielectric permittivity of the semiconductor with particle-polymer composites upon irradiation of light with a speci c wavelength changes the capacitance of the composite sandwiched between the two facing electrodes. Two physical theories of "interfacial polarization" and the "Maxwell-Wagner-Sillars (MWS) effect" at particle-polymer interfaces can explain these changes in the dielectric response of the composites upon light irradiation [32][33][34] .…”

“…In our previous study, a new type of capacitive photodetector was introduced that didn't exist before [29][30][31] .…”

Highly stabilized flexible transparent capacitive photodetector based on silver nanowire/graphene hybrid electrodes

“…To investigate the chemical stability, pH solutions were prepared by mixing a solution of hydrochloric acid (HCl) and sodium hydroxide (NaOH) with deionized water 23 . An inductance–capacitance–resistance (LCR) meter (HP4284A, Agilent) was used to measure the sample capacitance upon light irradiation 31 .…”

“…In our previous study, a new type of capacitive photodetector was introduced that didn’t exist before 29 – 31 . The fabricated device is based on a structure wherein ZnS:Cu particles are dispersed in a polymer film and transparent electrodes, which are AgNWs formed on both surfaces of a composite film.…”