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Prashant V. Kamat

Bio: Prashant V. Kamat is an academic researcher from University of Notre Dame. The author has contributed to research in topics: Racism & Excited state. The author has an hindex of 140, co-authored 725 publications receiving 79259 citations. Previous affiliations of Prashant V. Kamat include Indian Institute of Technology Kanpur & Council of Scientific and Industrial Research.


Papers
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TL;DR: The excitation of CuI in a CuI/CsPb Br3 film provides synergy between both CuI and CsPbBr3 inating the charge separation and recombination, and prebiasing experiments show the persistent and reversible “memory” effect of electrochemical bias on charge carrier lifetimes.
Abstract: Owing to its high hole conductivity and ease of preparation, CuI was among the first inorganic hole-transporting materials that were introduced early on in metal halide perovskite solar cells, but its full potential as a semiconductor material is still to be realized. We have now performed ultrafast spectroelectrochemical experiments on ITO/CuI electrodes to show the effect of applied bias on the excited-state dynamics in CuI. Under operating conditions, the recombination of excitons is dependent on the applied bias, and it can be accelerated by decreasing the potential from +0.6 to −0.1 V vs Ag/AgCl. Prebiasing experiments show the persistent and reversible “memory” effect of electrochemical bias on charge carrier lifetimes. The excitation of CuI in a CuI/CsPbBr3 film provides synergy between both CuI and CsPbBr3 in dictating the charge separation and recombination.

11 citations

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TL;DR: The ability of these thin films to incorporate redox-active species such as ferrocene from solution is demonstrated by cyclic voltammetry experiments and a linear dependence of the peak current for the oxidation of ferrocenes as a function of scan rate indicates that the ferrocENE is incorporated into the humic membrane.
Abstract: Polydisperse humic acid thin films on optically transparent electrodes (OTEs) have been prepared by electrophoretic deposition from a solution of Suwanee River humic acid (SHA) in ethanol/acetonitrile. The thickness of the film and the rate of deposition of SHA are dependent on the applied voltage and the concentration of the solution. Tapping-mode atomic force microscopy (TM-AFM) confirms the assembly of SHA aggregates on the electrode surface. The ability of these thin films to incorporate redox-active species such as ferrocene from solution is demonstrated by cyclic voltammetry experiments. A linear dependence of the peak current for the oxidation of ferrocene as a function of scan rate indicates that the ferrocene is incorporated into the humic membrane.

11 citations

Journal ArticleDOI
TL;DR: PulseRadiolysis and steady-state radiolysis experiments describing the radical and electron transfer reactions of C84 are reported here for the first time.
Abstract: Pulse radiolysis and steady-state radiolysis experiments describing the radical and electron transfer reactions of C84 are reported here for the first time. C84 reacts readily with radiolytically generated chloromethyl (•CCl3) and trichloromethylperoxyl (CCl3OO•) radicals in CCl4. The formation of the radical adduct has been confirmed from its characteristic absorption in the UV (320 nm) and visible (480 nm). Radical-induced oxidation in 1,2-dichloroethane (1,2-DCE) resulted in a short lived transient absorbing at 920 nm. Reduction of C84 in toluene/2-propanol/acetone could be conveniently followed by formation of an absorption band with an absorption maximum at 960 nm.

11 citations

Journal ArticleDOI
TL;DR: In this paper, the authors employ impedance spectroscopy to examine the mobility of charge carriers through each of the layers, and derive the derived mobility values provide a path to estimate the transition time of each charge carrier toward the emitting layer.
Abstract: Quantum dot light-emitting devices have emerged as an important technology for display applications. Their emission is a result of recombination between positive and negative charge carriers that are transported through the hole and electron conductive layers, respectively. The selection of electron or hole transport materials in these devices not only demands the alignment of energy levels between the layers but also balances the flow of electrons and holes toward the recombination sites. In this work, we examine a method for device optimization through control of the charge carrier kinetics. We employ impedance spectroscopy to examine the mobility of charge carriers through each of the layers. The derived mobility values provide a path to estimate the transition time of each charge carrier toward the emitting layer. We suggest that an optimal device structure can be obtained when the transition times of both charge carriers toward the active layer are similar. Finally, we examine our hypothesis by focusing on thickness optimization of the electron transport layer. Next-generation displays that use tiny semiconductor nanoparticles known as quantum dots to bolster color accuracy can reduce their power demands by following a new optimization procedure. To stimulate quantum dots to emit light, researchers typically sandwich them between two films that conduct either positive or negative charge. Now, Prashant Kamat from the University of Notre Dame in the United States and co-workers have developed an analytical technique that can predict the best arrangements of such sandwich-type structures. The team measured the speed of charge movement in the films with electrochemical spectroscopy, and then correlated the results with thickness measurements taken with electron microscopy. Their findings indicated that the dots were most efficient at converting electricity into light when film thicknesses were tweaked, so positive and negative charges moved toward the quantum dots at similar speeds. Quantum dot LED (light-emitting diode) optimization through the control of charge carriers’ kinetics is presented using impedance spectroscopy. The mobility of charge carriers through each one of the layers provide a path to estimate the transition time of each one of the charge carriers toward the emitting layer. By focusing on thickness optimization of electron transferring layer we can control the transition time of charge carriers and maximize radiative recombination.

10 citations


Cited by
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[...]

08 Dec 2001-BMJ
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

33,785 citations

Journal ArticleDOI
TL;DR: Two organolead halide perovskite nanocrystals were found to efficiently sensitize TiO(2) for visible-light conversion in photoelectrochemical cells, which exhibit strong band-gap absorptions as semiconductors.
Abstract: Two organolead halide perovskite nanocrystals, CH3NH3PbBr3 and CH3NH3PbI3, were found to efficiently sensitize TiO2 for visible-light conversion in photoelectrochemical cells. When self-assembled on mesoporous TiO2 films, the nanocrystalline perovskites exhibit strong band-gap absorptions as semiconductors. The CH3NH3PbI3-based photocell with spectral sensitivity of up to 800 nm yielded a solar energy conversion efficiency of 3.8%. The CH3NH3PbBr3-based cell showed a high photovoltage of 0.96 V with an external quantum conversion efficiency of 65%.

16,634 citations

Journal ArticleDOI
TL;DR: This work reviews the historical development of Transition metal dichalcogenides, methods for preparing atomically thin layers, their electronic and optical properties, and prospects for future advances in electronics and optoelectronics.
Abstract: Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.

13,348 citations

Journal ArticleDOI
TL;DR: A review of gold nanoparticles can be found in this article, where the most stable metal nanoparticles, called gold colloids (AuNPs), have been used for catalysis and biology applications.
Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346

11,752 citations

Journal ArticleDOI
Ryoji Asahi1, Takeshi Morikawa1, T. Ohwaki1, Koyu Aoki1, Y. Taga1 
13 Jul 2001-Science
TL;DR: Film and powders of TiO2-x Nx have revealed an improvement over titanium dioxide (TiO2) under visible light in optical absorption and photocatalytic activity such as photodegradations of methylene blue and gaseous acetaldehyde and hydrophilicity of the film surface.
Abstract: To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO 2- x N x have revealed an improvement over titanium dioxide (TiO 2 ) under visible light (wavelength 2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calculations and x-ray photoemission spectroscopy.

11,402 citations