1. Tunable emissive ▫$CsPbBr_3 /Cs_4PbBr_6$▫ quantum dots engineered by discrete phase transformation for enhanced photogating in field-effect phototransistorsHan Xiao, Siyuan Wan, Lin He, Junlong Zou, Andraž Mavrič, Yixi Wang, Marek Piotrowski, Anil Kumar Bandela, Paolo Samorì, Zhiming M. Wang, 2024, original scientific article Abstract: Precise control of quantum structures in hybrid nanocrystals requires advancements in scientific methodologies. Here, on the design of tunable CsPbBr3/Cs4PbBr6 quantum dots are reported by developing a unique discrete phase transformation approach in Cs4PbBr6 nanocrystals. Unlike conventional hybrid systems that emit solely in the green region, this current strategy produces adjustable luminescence in the blue (450 nm), cyan (480 nm), and green (510 nm) regions with high photoluminescence quantum yields up to 45%, 60%, and 85%, respectively. Concentration‐dependent studies reveal that phase transformation mechanisms and the factors that drive CsBr removal occur at lower dilutions while the dissolution–recrystallization process dominates at higher dilutions. When the polymer‐CsPbBr3/Cs4PbBr6 integrated into a field‐effected transistor the resulting phototransistors featured enhanced photosensitivity exceeding 105, being the highest reported for an n‐type phototransistor, while maintaining good transistor performances as compared to devices consisting of polymer‐CsPbBr3 NCs.
Keywords: crystallization mechanisms, dilution-induced kinetic trapping, photogating effect, phototransistors, quantum dots
Published in RUNG: 26.06.2024; Views: 1109; Downloads: 11
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4. Order fluctuation induced tunable light emission from carbon nano systemMohanachandran Nair Sindhu Swapna, Sankararaman S, 2019, original scientific article Abstract: The paper reports the thermal-induced order fuctuations, in a carbon nanosystem with carbon nanotubes (CNTs) synthesized
by the incomplete combustion of gingelly oil. The sample annealed at diferent temperatures (30–400 °C) is subjected to
various morphological and spectroscopic characterizations. The ultraviolet–visible spectroscopic and thermogravimetric
analyses reveal the CNTs in the sample. The high-resolution transmission electron microscopy (HR-TEM) also confrms the
formation of CNTs in the sample. The Raman spectrum and X-ray difraction pattern show the signature of multi-walled
to single-walled CNT transformation and thus an order fuctuation on annealing. The quantum yield of the sample, measured by integrating sphere method, yields 46.15% at an emission wavelength of 575 nm. When the excitation wavelength
is varied from 350 to 510 nm, the CIE coordinate moves from the white region to the yellowish-green region. The varying
amount of CNTs in the soot, upon annealing is found to vary the luminescence emission from the sample. The study reveals
the thermal-induced oscillatory order in carbon nanosystem with carbon nanotubes (CNTs) leading to tunable excitation/
thermal-dependent luminescence emission and thereby suggesting the possibility of converting the futile soot for fruitful
applications in photonics and nanoelectronics.
Keywords: Carbon nanosystem, Single-walled carbon nanotubes, Multi-walled carbon nanotubes, Raman spectroscopy, Thermogravimetric analysis, CIE plot, Quantum yield, gingelly oil
Published in RUNG: 05.07.2022; Views: 2202; Downloads: 0
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5. From futile to fruitful: Diesel soot as white light emitterMohanachandran Nair Sindhu Swapna, Sankararaman S, 2018, original scientific article Abstract: The present work describes a solution for the effective use of the hazardous particulate matter (diesel soot) from the internal combustion engines (ICEs) as a potential material emitting white light for white light emitting diodes (WLEDs). The washed soot samples are subjected to Field Emission Scanning Electron Microscopy (FESEM), High- Resolution Transmission Electron Microscopy (HR-TEM), Energy Dispersive Spectroscopy (EDS), UV-Visible, Photoluminescent (PL) Spectroscopy and quantum yield measurements. The CIE plot and Correlated Color Temperature (CCT) reveals the white fluorescence on photoexcitation. The sample on ultraviolet (UV) laser excitation, provides a visual confirmation of white light emission from the sample. The diesel soot collected from public transport buses of different years of manufacture invariably exhibit white fluorescence at an excitation of 350 nm. The sample show a quantum yield of 47.09%. The study is significant in the context of pollution and search for low-cost, rare-earth phosphor free material for white light emission and thereby turning the hazardous, futile material into a fruitful material that can be used for potential applications in photonics and electronics.
Keywords: White light emitter, Diesel soot, CIE plot, Quantum yield, Fluorescence
Published in RUNG: 30.06.2022; Views: 2197; Downloads: 0
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7. Magnetic Fields and Afterglows of BdHNe: Inferences from GRB 130427A, GRB 160509A, GRB 160625B, GRB 180728A, and GRB 190114CJorge Armando Rueda, Remo Ruffini, Mile Karlica, Rahim Moradi, Yu Wang, 2020, original scientific article Abstract: GRB 190114C is the first binary-driven hypernova (BdHN) fully observed from initial supernova (SN) appearance to the final emergence of the optical SN signal. It offers an unprecedented testing ground for the BdHN theory, which is here determined and further extended to additional gamma-ray bursts (GRBs). BdHNe comprise two subclasses of long GRBs, with progenitors a binary system composed of a carbon–oxygen star (COcore) and a neutron star (NS) companion. The COcore explodes as an SN, leaving at its center a newborn NS (νNS). The SN ejecta hypercritically accretes on both the νNS and the NS companion. BdHNe I are very tight binaries, where the accretion leads the companion NS to gravitationally collapse into a black hole (BH). In BdHN II, the accretion rate onto the NS is lower, so there is no BH formation. We observe the same afterglow structure for GRB 190114C and other selected examples of BdHNe I (GRB 130427A, GRB 160509A, GRB 160625B) and for BdHN II (GRB 180728A). In all cases, the afterglows are explained via the synchrotron emission powered by the νNS, and their magnetic field structures and their spin are determined. For BdHNe I, we discuss the properties of the magnetic field embedding the newborn BH, which was inherited from the collapsed NS and amplified during the gravitational collapse process, and surrounded by the SN ejecta.
Keywords: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, General Relativity and Quantum Cosmology
Published in RUNG: 20.07.2020; Views: 3560; Downloads: 0
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8. About TimeUna Rebić, 2016, master's thesis Abstract: The practical work of my master project about time was carried out as processbased
experiments in practice. As a result, the thesis is a combination of
theoretical research taken from several fields—examining the notion of time from
perspective of psychology, sociology, science and spirituality. Alongside mentioned
research the thesis pairs artistic practices associated with each field discussed—
considering most significant artist and his/her practice or project(s) in which they
explore time. The third layer of the thesis pairs each section with my own personal
practice through experiments carried out in the process—each exploring time from
a different perspective. Since the thesis is the final project of the study developed
within a certain time frame, the last chapter discusses how I approached this
project in regard to my artistic practice.
Keywords: time, perception, On Kawara, sociology, speed, Hamish Fulton, quantum
entanglement, arrow of time, Hiroshi Sugimoto, spirituality, consciousness, Marina
Abramović, Ulay
Published in RUNG: 14.09.2016; Views: 5577; Downloads: 1
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