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Dual Wavelength (Ultraviolet and Green) Photodetectors Using Solution Processed Zinc Oxide Nanoparticles
journal contribution
posted on 2017-09-26, 00:00 authored by Mohammed A. Ibrahem, Emanuele Verrelli, Khue T. Lai, Georgios Kyriakou, Adam F. Lee, Mark A. Isaacs, Fei Cheng, Mary O’NeillNarrow-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.
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applicationcontrollabilityPhotodetectordefectvacancyZnO nanocrystals2.25 eVwavelengthoxygen vacanciesdecay transientspixelate photodetectorsspectrumphotocurrent responsivitystorageobject discriminationwidthUltravioletDual Wavelengthdonorformationscalable photolithographic approachcarbonate surface speciesSolution Processed Zinc Oxide Nanoparticles Narrow-band photoconductivityZnO pixels0.16 eVelectron transfersolution-processedresponsecarbon dioxidesubstratecorrelatesensor modecolor imagingmodelband-edge
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