Dual Wavelength (Ultraviolet and Green) Photodetectors Using Solution Processed Zinc Oxide Nanoparticles

Abstract

Narrow-band photoconductivity with a spectral width of 0.16 eV is obtained from solution-processed colloidal ZnO nanocrystals beneath the band-edge at 2.25 eV. A new model involving electron transfer from deep defects to discrete shallow donors is introduced to explain the narrow spectrum and the exponential form of the current rise and decay transients. The defects are tentatively assigned to neutral oxygen vacancies. The photocurrent responsivity can be enhanced by storage in air, and this correlates with the formation of carbonate surface species by capture of carbon dioxide during storage. This controllability is exploited to develop a low-cost and scalable photolithographic approach to pixelate photodetectors for applications such as object discrimination, sensing, etc. The spectral response can be spatially patterned so that dual (ultraviolet and green) and single (ultraviolet only) wavelength detecting ZnO pixels can be produced on the same substrate. This presents a new sensor mode with applications in security or full color imaging.

Surface-Engineered Nanostructure-Based Efficient Nonpolar GaN Ultraviolet Photodetectors

“…Hence, the decrease in decay time of the chemically engineered UV PDs indicates reduction in defect states in the nanostructured films. Also, the response time (both on rise and decay) of the fabricated UV PDs is better than most of the previously reported low-dimensional nanostructured PDs, ranging from seconds to tens of minutes or even hours, which is highlighted in Table . − Therefore, by utilizing these surface-engineered structures, the response time and recovery speed of MSM-based GaN UV PDs can be dramatically reduced, which makes them ideal for the faster switching applications.…”

Self-Powered Dual-Color UV–Green Photodetectors Based on SnO2 Millimeter Wire and Microwires/CsPbBr3 Particle Heterojunctions

“…However, a single PD usually has a specific spectral response range. To satisfy some special requirements in applications with regard to full color imaging and so on, , investigations on PDs with dual wavelengths are particularly important.…”

Sensing of Oxygen Partial Pressure in Air with ZnO Nanoparticles

“…The demand for the miniaturized oxygen partial pressure sensor is becoming increasingly high due to the low signal-to-noise ratio, low power consumption, reduced weight, and low cost, especially for integrated applications [1,33,34]. The patterning of ZnO NPs have been attempted by various techniques such as inkjet printing [35], imprinting [36], laser ablation [37], and photolithography [37,38]. However, the patterning of ZnO NPs is still challenged by the mechanical stability, chemical resistivity, and cost, etc.…”