En route to a unified model for photo-electrochemical reactor optimisation. I - Photocurrent and H2 yield predictions

AbstractTime-resolved all-optical techniques are used to measure the density and temperature dependence of electron-hole recombination in an InAs/GaInSb/InAs/AlGaInAsSb strain-balanced superlattice grown by molecular beam expitaxy on GaSb. This 4 μm bandgap structure, which has been designed for suppressed Auger recombination, is a candidate material for the active region of mid-infrared lasers. While carrier lifetime measurements at room temperature show unambiguous evidence of Auger recombination, the extracted Auger recombination rates are considerably lower than those reported for bulk materials of comparable bandgap energy. We find that the Auger rate saturates at carrier densities comparable to those required for degeneracy of the valence band, illustrating the impact of Fermi statistics on the Auger process. The measured results are compared with theoretical Auger rates computed using a band structure obtained from a semi-empirical 8-band K.p model. We find excellent agreement between theoretical and experimental results when Umklapp processes in the growth direction are included in the calculation. Measured recombination rates from 50 to 300 K are combined with calculated threshold carrier densities to determine a material To value for the superlattice.

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Accumulation of Deep Traps at Grain Boundaries in Halide Perovskites

10.26434/chemrxiv.8058413.v1 ◽

2019 ◽

Author(s):

Ji-Sang Park ◽

Joaquín Calbo ◽

Young-Kwang Jung ◽

lucy whalley ◽

Aron Walsh

Keyword(s):

Grain Boundaries ◽

Perovskite Solar Cells ◽

Extended Defects ◽

Trap States ◽

Bulk Crystals ◽

Recombination Rates ◽

Electron Hole ◽

Interstitial Defects ◽

Halide Perovskites ◽

Hole Recombination

<div> <div> <div> <p>The behaviour of grain boundaries in polycrystalline halide perovskite solar cells remains poorly understood. Whereas theoretical studies indicate that grain boundaries are not active for electron-hole recombination, there have been observations of higher non-radiative recombination rates involving these extended defects. We find that iodine interstitial defects, which have been established as a recombination center in bulk crystals, tend to segregate at planar defects in CsPbI3. First-principles calculations show that enhanced structural relaxation of the defects at grain boundaries results in increased stability (higher concentration) and deeper trap states (faster recombination). We show how the grain boundary can be partly passivated by halide mixing or extrinsic doping, which replaces or suppresses the formation of trap states close to the grain boundaries.<br></p> </div> </div> </div>

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Size dependence of the electron-hole recombination rates in semiconductor quantum dots

Physical Review B ◽

10.1103/physrevb.67.045313 ◽

2003 ◽

Vol 67 (4) ◽

Cited By ~ 21

Author(s):

S. Corni ◽

M. Braskén ◽

M. Lindberg ◽

J. Olsen ◽

D. Sundholm

Keyword(s):

Quantum Dots ◽

Size Dependence ◽

Semiconductor Quantum Dots ◽

Recombination Rates ◽

Electron Hole ◽

Hole Recombination

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Accumulation of Deep Traps at Grain Boundaries in Halide Perovskites

10.26434/chemrxiv.8058413 ◽

2019 ◽

Author(s):

Ji-Sang Park ◽

Joaquín Calbo ◽

Young-Kwang Jung ◽

lucy whalley ◽

Aron Walsh

Keyword(s):

Grain Boundaries ◽

Perovskite Solar Cells ◽

Extended Defects ◽

Trap States ◽

Bulk Crystals ◽

Recombination Rates ◽

Electron Hole ◽

Interstitial Defects ◽

Halide Perovskites ◽

Hole Recombination

<div> <div> <div> <p>The behaviour of grain boundaries in polycrystalline halide perovskite solar cells remains poorly understood. Whereas theoretical studies indicate that grain boundaries are not active for electron-hole recombination, there have been observations of higher non-radiative recombination rates involving these extended defects. We find that iodine interstitial defects, which have been established as a recombination center in bulk crystals, tend to segregate at planar defects in CsPbI3. First-principles calculations show that enhanced structural relaxation of the defects at grain boundaries results in increased stability (higher concentration) and deeper trap states (faster recombination). We show how the grain boundary can be partly passivated by halide mixing or extrinsic doping, which replaces or suppresses the formation of trap states close to the grain boundaries.<br></p> </div> </div> </div>

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Photoelectrochemical performance and ultrafast dynamics of photogenerated electrons and holes in highly titanium-doped hematite

Physical Chemistry Chemical Physics ◽

10.1039/d0cp04954a ◽

2020 ◽

Vol 22 (46) ◽

pp. 27450-27457

Author(s):

Alexander T. Paradzah ◽

Kelebogile Maabong-Tau ◽

Mmantsae Diale ◽

Tjaart P. J. Krüger

Keyword(s):

Ultrafast Dynamics ◽

Recombination Rates ◽

Photoelectrochemical Performance ◽

Electron Hole ◽

Photogenerated Electrons ◽

Hole Recombination

We present electron–hole recombination rates in improved hematite photoelectrodes containing pseudobrookite and titania overlayers due to high doping.

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Optically Detected Magnetic Resonance and Double Beam Photoluminescence of CdS/HgS/CdS Nanoparticles

MRS Proceedings ◽

10.1557/proc-536-257 ◽

1998 ◽

Vol 536 ◽

Author(s):

H. Porteanu ◽

A. Glozman ◽

E. Lifshitz ◽

A. Eychmüller ◽

H. Weller

Keyword(s):

Optical Properties ◽

Magnetic Resonance ◽

Cds Nanoparticles ◽

Electron Hole ◽

Cladding Layer ◽

Double Beam ◽

Optically Detected Magnetic Resonance ◽

Optically Detected ◽

Cladding Layers ◽

Hole Recombination

AbstractCdS/HgS/CdS nanoparticles consist of a CdS core, epitaxially covered by one or two monolayers of HgS and additional cladding layers of CdS. The present paper describes our efforts to identify the influence of CdS/HgS/CdS interfaces on the localization of the photogenerated carriers deduced from the magneto-optical properties of the materials. These were investigated by the utilization of optically detected magnetic resonance (ODMR) and double-beam photoluminescence spectroscopy. A photoluminescence (PL) spectrum of the studied material, consists of a dominant exciton located at the HgS layer, and additional non-excitonic band, presumably corresponding to the recombination of trapped carriers at the interface. The latter band can be attenuated using an additional red excitation. The ODMR measurements show the existence of two kinds of electron-hole recombination. These electron-hole pairs maybe trapped either at a twin packing of a CdS/HgS interface, or at an edge dislocation of an epitaxial HgS or a CdS cladding layer.

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Pre-Industrial Experience in Solar Photocatalytic Mineralization of Real Wastewaters. Application to Pesticide Container Recycling

Water Science & Technology ◽

10.2166/wst.1999.0583 ◽

1999 ◽

Vol 40 (4-5) ◽

pp. 123-130 ◽

Cited By ~ 2

Author(s):

S. Malato ◽

J. Blanco ◽

C. Richter ◽

B. Milow ◽

M. I. Maldonado

Keyword(s):

Organic Contaminants ◽

Toxic Waste ◽

Experimental Plant ◽

Electron Hole ◽

Particulate Suspensions ◽

Photocatalytic System ◽

Commercial Pesticide ◽

Pesticide Container ◽

By Products ◽

Hole Recombination

Particulate suspensions of TiO2 irradiated with natural solar tight in a large experimental plant catalyse the oxidation of organic contaminants. The problem in using TiO2 as a photocatalyst is electron/hole recombination. One strategy for inhibiting e−/h+ recombination is to add other (irreversible) electron acceptors to the reaction. In many highly toxic waste waters where degradation of organic pollutants is the major concern, the addition of an inorganic anion to enhance the organic degradation rate may be justified. For better results, these additives should fulfil the following criteria: dissociate into harmless by-products and lead to the formation of ·OH or other oxidising agents. In this paper, we attempt to demonstrate the optimum conditions for the treatment of commercial pesticide rinsates found in the wastewater produced by a pesticide container recycling plant. The experiments were performed in one of the pilot plants of the largest solar photocatalytic system in Europe, the Detoxification Plants of the Plataforma Solar de Almería (PSA), in Spain. After testing ten different commercial pesticides, results show that peroxydisulphate enhances the photocatalytic miniralization of all of them. This study is part of an extensive project focused on the design of a solar photocatalytic plant for decontamination of agricultural rinsates in Almería (Spain).

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