Self Powered Highly Enhanced Dual Wavelength ZnO@CdS Core–Shell Nanorod Arrays Photodetector: An Intelligent Pair

Abstract

On the face of the impending energy crisis, developing low-energy or even zero-energy photoelectronic devices is extremely important. A multispectral photosensitivity feature of a self-powered device provides an additional powerful tool. We have developed an unprecedented high performance dual wavelength self-powered ZnO@CdS/PEDOT:PSS core-shell nanorods array photodetector through a simple aqueous chemical method wherein a suitable band alignment between an intelligent material pair, i.e. ZnO and CdS, has been utilized. Besides a noteworthy advantage of the devices being that they show a very sharp and prominent dual wavelength photosensitivity, both the ultraviolet and visible light sensitivity (ratio of current under illumination (Iphoto)/current under dark (Idark)) of the device are two orders of higher magnitude than those of pristine ZnO, attaining values of 2.8 × 10(3) and 1.07 × 10(3), respectively. At the same time, temporal responses faster than 20 ms could be achieved with these solution-processed photodetectors. The present study provides a very important direction to engineer core-shell nanostructured devices for dual wavelength high photosensitivity.

Designing CdS/Se heterojunction as high-performance self-powered UV-visible broadband photodetector

“…Table I summarizes the comparative parameters of our n-CdS/p-Se heterojunction photodiode and other CdS or Se based heterojunction devices reported in the previous literature. 16,23,24,[30][31][32][33][34][35] The performance of our devices is comparable to that of the previously reported state-of-the-art devices. The superior performance can be attributed to the following reasons: (i) The direct and small bandgap and high absorption coefficient ensure that CdS and Se are ideal photodetecting semiconductors.…”

Novel UV–Visible Photodetector in Photovoltaic Mode with Fast Response and Ultrahigh Photosensitivity Employing Se/TiO2 Nanotubes Heterojunction

“…1D semiconductor nanostructures have stimulated much attention in high performance photodetectors (PDs) owing to the pronounced surface effects (i.e., oxygen adsorption/ desorption) originating from the large surface-to-volume ratio and a Debye length comparable to their small size for 1D semiconductor nanostructures. [1][2][3][4][5] Generally, the large surface-to-volume ratio can significantly increase the number of surface trap states and prolong the photocarrier lifetime, leading to good sensitivity and high responsivity. [1] However, the surface effects also extend the rise/decay time due to slow oxygen adsorption/desorption processes, thus hindering the wire-free route for artificial vision, etc.…”

Self‐Powered UV Photodetector Array Based on P3HT/ZnO Nanowire Array Heterojunction

“…Generally, an external power supply is required to prevent the recombination of photogenerated charge carriers (electron–hole pairs) for desirable photoresponse, which limits the miniaturization of photodetectors as well as their long‐term application in large‐scale arrays . It is thus of great importance to achieve self‐powered operation at zero bias, either through integrating the photodetectors with triboelectric/piezoelectric nanogenerators or by utilizing intrinsic photovoltaic effect . For self‐powered UV photodetectors driven by the photovoltaic effect, ZnO nanowires are a promising candidate, owing to its band gap of 3.35 eV suitable for UV absorption, 1D nanostructure superior for prolonging lifetime of charge carriers, and noncentral‐symmetric crystal structure beneficial for piezoelectric or pyroelectric polarization .…”

“…For self‐powered UV photodetectors driven by the photovoltaic effect, ZnO nanowires are a promising candidate, owing to its band gap of 3.35 eV suitable for UV absorption, 1D nanostructure superior for prolonging lifetime of charge carriers, and noncentral‐symmetric crystal structure beneficial for piezoelectric or pyroelectric polarization . Until now, various self‐powered photodetectors based on ZnO nanowires have been reported with high responsivity . In particular, accelerated separation of charge carriers have been observed in ZnO‐based organic–inorganic heterojunctions due to the formation of built‐in electric field at the heterojunctions .…”