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Mulder, J.T. (author), Kirkwood, N.R.M. (author), De Trizio, Luca (author), Li, Chen (author), Bals, Sara (author), Manna, L. (author), Houtepen, A.J. (author)Indium phosphide quantum dots (QDs) have drawn attention as alternatives to cadmium- and lead-based QDs that are currently used as phosphors in lamps and displays. The main drawbacks of InP QDs are, in general, a lower photoluminescence quantum yield (PLQY), a decreased color purity, and poor chemical stability. In this research, we attempted...journal article 2020
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Crisp, R.W. (author), Hashemi, Fatemeh S.M. (author), Alkemade, J. (author), Kirkwood, N.R.M. (author), Grimaldi, G. (author), Kinge, S.S. (author), Siebbeles, L.D.A. (author), van Ommen, J.R. (author), Houtepen, A.J. (author)To improve the stability and carrier mobility of quantum dot (QD) optoelectronic devices, encapsulation or pore infilling processes are advantageous. Atomic layer deposition (ALD) is an ideal technique to infill and overcoat QD films, as it provides excellent control over film growth at the sub-nanometer scale and results in conformal...journal article 2020
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Kirkwood, N.R.M. (author), De Backer, Annick (author), Longo, Alessandro (author), Geuchies, J.J. (author), Mulder, J.T. (author), Renaud, N. (author), Bals, Sara (author), Manna, L. (author), Houtepen, A.J. (author)Zinc is routinely employed in the synthesis of InP quantum dots (QDs) to improve the photoluminescence efficiency and carrier mobility of the resulting In(Zn)P alloy nanostructures. The exact location of Zn in the final structures and the mechanism by which it enhances the optoelectronic properties of the QDs are debated. We use synchrotron X...journal article 2020
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van der Stam, W. (author), Grimaldi, G. (author), Geuchies, J.J. (author), Gudjónsdóttir, S. (author), Van Uffelen, Pieter T. (author), Van Overeem, Mandy (author), Brynjarsson, Baldur (author), Kirkwood, N.R.M. (author), Houtepen, A.J. (author)In this work, we systematically study the spectroelectrochemical response of CdSe quantum dots (QDs), CdSe/CdS core/shell QDs with varying CdS shell thicknesses, and CdSe/CdS/ZnS core/shell/shell QDs in order to elucidate the influence of localized surface trap states on the optoelectronic properties. By correlating the differential...journal article 2019
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Grimaldi, G. (author), Van Den Brom, Mark J. (author), du Fossé, I. (author), Crisp, R.W. (author), Kirkwood, N.R.M. (author), Gudjónsdóttir, S. (author), Geuchies, J.J. (author), Kinge, S.S. (author), Siebbeles, L.D.A. (author), Houtepen, A.J. (author)Colloidal quantum dots (QDs) allow great flexibility in the design of optoelectronic devices, thanks to their size-dependent optical and electronic properties and the possibility to fabricate thin films with solution-based processing. In particular, in QD-based heterojunctions, the band gap of both components can be controlled by varying the...journal article 2019
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Grimaldi, G. (author), Geuchies, J.J. (author), van der Stam, W. (author), du Fossé, I. (author), Brynjarsson, Baldur (author), Kirkwood, N.R.M. (author), Kinge, S.S. (author), Siebbeles, L.D.A. (author), Houtepen, A.J. (author)In transient absorption (TA) measurements on Cd-chalcogenide quantum dots (QDs), the presence of a band-edge (BE) bleach signal is commonly attributed entirely to conduction-band electrons in the 1S(e) state, neglecting contributions from BE holes. While this has been the accepted view for more than 20 years, and has often been used to...journal article 2019
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Grimaldi, G. (author), Crisp, R.W. (author), Ten Brinck, Stephanie (author), Zapata, Felipe (author), van Ouwendorp, M. (author), Renaud, N. (author), Kirkwood, N.R.M. (author), Evers, W.H. (author), Kinge, S.S. (author), Infante, Ivan (author), Siebbeles, L.D.A. (author), Houtepen, A.J. (author)Thermalization losses limit the photon-to-power conversion of solar cells at the high-energy side of the solar spectrum, as electrons quickly lose their energy relaxing to the band edge. Hot-electron transfer could reduce these losses. Here, we demonstrate fast and efficient hot-electron transfer between lead selenide and cadmium selenide...journal article 2018
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Crisp, R.W. (author), Grimaldi, G. (author), De Trizio, Luca (author), Evers, W.H. (author), Kirkwood, N.R.M. (author), Kinge, Sachin (author), Manna, L. (author), Siebbeles, L.D.A. (author), Houtepen, A.J. (author)Indium antimonide (InSb) quantum dots (QDs) have unique and interesting photophysical properties, but widespread experimentation with InSb QDs is lacking due to the difficulty in synthesizing this material. The key experimental challenge in fabricating InSb QDs is preparing a suitable Sb-precursor in the correct oxidation state that reacts...journal article 2018
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Gudjónsdóttir, S. (author), van der Stam, W. (author), Kirkwood, Nicholas (author), Evers, W.H. (author), Houtepen, A.J. (author)Control over the charge density is very important for implementation of colloidal semiconductor nanocrystals into various optoelectronic applications. A promising approach to dope nanocrystal assemblies is charge injection by electrochemistry, in which the charge compensating electrolyte ions can be regarded as external dopant ions. To gain...journal article 2018
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van der Stam, W. (author), de Graaf, M. (author), Gudjónsdóttir, S. (author), Geuchies, J.J. (author), Dijkema, J.J. (author), Kirkwood, N.R.M. (author), Evers, W.H. (author), Longo, Alessandro (author), Houtepen, A.J. (author)The processes that govern radiative recombination in ternary CuInS<sub>2</sub> (CIS) nanocrystals (NCs) have been heavily debated, but recently, several research groups have come to the same conclusion that a photoexcited electron recombines with a localized hole on a Cu-related trap state. Furthermore, it has been observed that single CIS...journal article 2018
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Crisp, R.W. (author), Kirkwood, N.R.M. (author), Grimaldi, G. (author), Kinge, Sachin (author), Siebbeles, L.D.A. (author), Houtepen, A.J. (author)InP and InZnP colloidal quantum dots (QDs) are promising materials for application in light-emitting devices, transistors, photovoltaics, and photocatalytic cells. In addition to possessing an appropriate bandgap, high absorption coefficient, and high bulk carrier mobilities, the intrinsic toxicity of InP and InZnP is much lower than for...journal article 2018
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Kirkwood, N.R.M. (author), Monchen, J.O.V. (author), Crisp, R.W. (author), Grimaldi, G. (author), Bergstein, Huub A.C. (author), du Fossé, I. (author), van der Stam, W. (author), Infante, Ivan (author), Houtepen, A.J. (author)Energy levels in the band gap arising from surface states can dominate the optical and electronic properties of semiconductor nanocrystal quantum dots (QDs). Recent theoretical work has predicted that such trap states in II-VI and III-V QDs arise only from two-coordinated anions on the QD surface, offering the hypothesis that Lewis acid (Z...journal article 2018
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van der Stam, W. (author), du Fossé, I. (author), Grimaldi, G. (author), Monchen, J.O.V. (author), Kirkwood, Nicholas (author), Houtepen, A.J. (author)The photoluminescence (PL) quantum yield of semiconductor nanocrystals (NCs) is hampered by in-gap trap states due to dangling orbitals on the surface of the nanocrystals. While crucial for the rational design of nanocrystals, the understanding of the exact origin of trap states remains limited. Here, we treat CdTe nanocrystal films with...journal article 2018
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Pietra, F. (author), Kirkwood, N.R.M. (author), De Trizio, L. (author), Hoekstra, Anne W. (author), Kleibergen, Lennart (author), Renaud, N. (author), Koole, Rolf (author), Baesjou, Patrick J. (author), Manna, L. (author), Houtepen, A.J. (author)In this work, we demonstrate that a preferential Ga-for-Zn cation exchange is responsible for the increase in photoluminescence that is observed when gallium oleate is added to InZnP alloy QDs. By exposing InZnP QDs with varying Zn/In ratios to gallium oleate and monitoring their optical properties, composition, and size, we conclude that Ga3+...journal article 2017
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Koenis, J.P. (author), Kirkwood, T.F. (author)Salt intrusion into the Rotterdamsche Waterweg plays a major role in the water management of the Netherlands. The objective of the modeling described in this volume is to estimate the salt concentration caused by salt intrusion from the sea of water at various points. Chapter 2 gives an overview of the modeling. The sources of the data used are...report 1982
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Kirkwood, T.F. (author)When water is extracted from rivers to supply users such as agriculture, the resulting sedimentation may cause costs for shipping or dredging. This volume describes three models, the Sedimentation Model, Dredging Cost Model, and Sedimentation Loss Function Model, built to estimate these costs for tactics which involve extractions from the Waal...report 1981
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Kirkwood, T.F. (author), Abrahamse, A.F. (author), Repnau, T. (author)Some of the tactics considered in PAWN involve raising the water level in two large freshwater lakes (the IJsselmeer and Markermeer) in order to store more fresh water for use in the summer dry period. This volume describes models that PAWN developed and used to estimate the change in safety, as measured by the probability of flooding, which...report 1981
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Goeller, B.F. (author), Abrahamse, A.F. (author), Bigelow, J.H. (author), Bolten, J.G. (author), De Ferranti, D.M. (author), De Haven, J.C. (author), Kirkwood, T.F. (author), Petruschell, R.L. (author)The first volume in a series of reports describing the methodology and results of a joint research venture between RAND and the Netherlands Rijkswaterstaat. The POLANO project was founded to help the Dutch government analyze the different alternatives (open, closed, and storm-surge barrier cases) for protecting the Oosterschelde region from...report 1977
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Abrahamse, A.F. (author), Bigelow, J.H. (author), Gladstone, R.J. (author), Goeller, B.F. (author), Kirkwood, T.F. (author), Petruschell, R.L. (author)The second volume in a series of reports describing the methodology and results of a joint research venture between RAND and the Netherlands Rijkswaterstaat. The POLANO project was founded to help the Dutch government analyze the different alternatives (open, closed, and storm-surge barrier cases) for protecting the Oosterschelde region from...report 1977