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219 results on '"Yun, Ju-Hyung"'

26. Expanding the Spectral Responsivity of Photodetectors via the Integration of CdSe/ZnS Quantum Dots and MEH−PPV Polymer Composite.

Author

Tran, Thanh Thao, Nguyen, Ha Trang, Sharma, Ankush, Cho, Young-Bin, Kumar, Manjeet, and Yun, Ju-Hyung

Subjects
ACTION spectrum, QUANTUM dots, SPECTRAL sensitivity, VISIBLE spectra, ENERGY transfer
Abstract

This study investigates the energy transfer mechanism between the organic polymer poly(2-methoxy-5(2'-ethyl)heroxyphenylenevinylene) (MEH−PPV) and CdSe/ZnS core-shell quantum dots (CdSe/ZnS CSQDs). Additionally, a hybrid ZnO-based photodetector (PD) is fabricated using the composite of MEH−PPV and CdSe/ZnS CSQDs, aiming to gain deeper insights. The combination of MEH−PPV and CdSe/ZnS CSQDs facilitates a broad spectral response in PDs, spanning from the ultraviolet (UV) to the visible range. In particular, PDs with QDs in the composite demonstrate notably excellent photosensitivity to both ultraviolet (UV) light (365 nm) (~5 fold) and visible light (505 nm) (~3 fold). [ABSTRACT FROM AUTHOR]

Published
2024
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42. Pyro‐Phototronic Effect in n‐Si/p‐MoO3−x Heterojunction: an Approach to Improve the Photoresponse of the Ultraviolet Photodetector.

Author

Bhatt, Vishwa, Sahare, Sanjay, Kumar, Manjeet, Lee, Shern-Long, Kumar, Sunil, and Yun, Ju-Hyung

Subjects
HETEROJUNCTIONS, PHOTODETECTORS, PHOTOELECTRIC effect, OPTICAL communications, HETEROSTRUCTURES
Abstract

The pyro‐phototronic effect plays a crucial role in UV photodetection to enhance the overall device performance. Herein, the pyro‐phototronic effect is demonstrated for the first time in n‐Si/MoO3−x heterostructures. Vertically grown 2D‐MoO3−x microstructures are synthesized that show a centrosymmetric structure. Commonly, non‐centrosymmetric structures show a pyroelectric polarization effect; however, in the present work, authors have shown such a synergetic effect in a centrosymmetric MoO3−x‐based heterojunction. The fabricated device depicts a type I heterojunction that helps to reduce the response time and consequently minimizes charge‐carrier recombination losses. UV photodetection is measured with very low power, and significant device performances are observed under varying light intensities. The maximum responsivity and detectivity are attained up to 4.4 mA W−1 and 5.5 × 1010 Jones under photoelectric effects. Additionally, the maximum responsivity and detectivity are attained up to 7.82 mA W−1 and 1011 Jones under the pyro‐phototronic effect. Herein, an in‐depth understanding of the pyro‐phototronic effect in working phenomenon in type I heterojunction is provided. Such a mechanism can be explored in different heterojunctions to enhance photodetection performance in ultrafast light communications. [ABSTRACT FROM AUTHOR]

Published
2023
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45. Investigation of efficient photoconduction and enhanced luminescence characteristics of Ce‐doped ZnO nanophosphors for UV sensors.

Author

Kumar, Rajesh, Mishra, Sheo K., Kumar, Arvind, Kumar, Indresh, Kumar, Manjeet, Yun, Ju‐Hyung, Kumar, Sunil, and Singh, Abhimanyu Kumar

Abstract

This study involves the single‐step, mass‐scale productive synthesis, photoconduction, and luminescence characteristics of pure and cerium rare‐earth‐ion‐doped ZnO (CZO) nanophosphors with different Ce concentrations (Ce: 0, 2, 4, 6, and 8 wt.%) synthesized using the solid‐state reaction method. The synthesized nanophosphors were characterized for their structural, morphological, optical, and photoconductivity (PC) properties using X‐ray diffraction (XRD), field‐effect scanning electron microscopy (FE‐SEM), energy dispersive spectroscopy, Fourier‐transform infrared (FT‐IR), photoluminescence (PL), and PC measurements. The sharp diffraction peaks of XRD results exhibit the formation of crystalline hexagonal wurtzite ZnO nanostructures. The decrease in diffraction peak intensities of CZO with an increase in Ce concentrations signifies the deterioration of the ZnO crystal. FE‐SEM images exhibit the good crystalline quality of nanophosphors composed of spherical‐ and elongated‐shaped nanoparticles that are distributed consistently on the surface. The energy dispersive X‐ray pattern of the 4 wt.% Ce‐doped ZnO (CZO4) sample confirms the doping of Ce in ZnO. The presence of chemical bonds and functional groups corresponds to transmittance peaks established using FT‐IR spectroscopy. Deconvoluted PL spectra show two major emission peaks, one in the UV region, which is near‐band‐edge, and the other in the visible region ranging from ~456 to 561 nm. In PC studies, current–voltage (I–V) and current–time (I–T) characteristics, that is, rise/decayin current under dark as well as UV light conditions, are also investigated. Efficient photoconduction is observed in CZO samples. The obtained results indicate the suitability to luminescent and photosensor applications. [ABSTRACT FROM AUTHOR]

Published
2023
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