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

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.

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

2017 ◽  
Vol 5 (43) ◽  
pp. 22683-22696 ◽  
Author(s):  
Franky E. Bedoya-Lora ◽  
Anna Hankin ◽  
Geoff H. Kelsall
Keyword(s):  
Electrochemical Cell ◽  
Cell Model ◽  
Bubble Formation ◽  
Electrochemical Reactor ◽  
Photon Flux ◽  
Recombination Rates ◽  
Electron Hole ◽  
Gas Desorption ◽  
H2 Yield ◽  
Hole Recombination

A photo-electrochemical cell model was developed accounting for photon flux, electron–hole recombination rates, gas desorption, bubble formation and cross-over losses.

Auger Recombination in Antimony-Based, Strain-Balanced, Narrow-Band-Gap Superlattics

1997 ◽  
Vol 484 ◽  
Author(s):  
J. T. Olesberg ◽  
Thomas F. Boggess ◽  
S. A. Anson ◽  
D.-J. Jan ◽  
M. E. Flatté ◽  
...  
Keyword(s):  
Auger Recombination ◽  
Growth Direction ◽  
Bandgap Energy ◽  
Recombination Rates ◽  
Electron Hole ◽  
Time Resolved ◽  
All Optical ◽  
Semi Empirical ◽  
The Impact ◽  
Hole Recombination

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.

Accumulation of Deep Traps at Grain Boundaries in Halide Perovskites

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>

scholarly journals Ultrafast Dynamics of Defect-Assisted Electron–Hole Recombination in Monolayer MoS2

Nano Letters ◽  
2014 ◽  
Vol 15 (1) ◽  
pp. 339-345 ◽  
Author(s):  
Haining Wang ◽  
Changjian Zhang ◽  
Farhan Rana
Keyword(s):  
Ultrafast Dynamics ◽  
Monolayer Mos2 ◽  
Electron Hole ◽  
Hole Recombination

Accumulation of Deep Traps at Grain Boundaries in Halide Perovskites

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>

scholarly journals Ternary Composite of Co-Doped CdSe@electrospun Carbon Nanofibers: A Novel Reusable Visible Light-Driven Photocatalyst with Enhanced Performance

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 348 ◽  
Author(s):  
Gopal Panthi ◽  
Oh Hoon Kwon ◽  
Yun-Su Kuk ◽  
Kapil Raj Gyawali ◽  
Yong Wan Park ◽  
...  
Keyword(s):  
Carbon Nanofibers ◽  
Photocatalytic Performance ◽  
Electrospun Nanofibers ◽  
Electron Hole ◽  
Ternary Composite ◽  
Photogenerated Electrons ◽  
Visible Light Driven ◽  
Photocatalytic Applications ◽  
Hole Recombination

In this work, flexible ternary composites of cobalt-doped cadmium selenide/electrospun carbon nanofibers (Co-CdSe@ECNFs) for photocatalytic applications were fabricated successfully via electrospinning, followed by carbonization. For the fabrication of the proposed photocatalysts, Co-CdSe nanoparticles were grown in situ on the surface of ECNFs during the carbonization of precursor electrospun nanofibers obtained by dispersing Se powder in the electrospinning solution of polyacrylonitrile/N,N-Dimethylformamide (PAN/DMF) containing Cd2+ and Co2+. The photocatalytic performance of synthesized samples is investigated in the photodegradation of methylene blue (MB) and rhodamine B (RhB) dyes. Experimental results revealed the superior photocatalytic efficiency of Co-CdSe@ECNFs over undoped samples (CdSe@ECNFs) due to the doping effect of cobalt, which is able to capture the photogenerated electrons to prevent electron–hole recombination, thereby improving photocatalytic performance. Moreover, ECNFs could play an important role in enhancing electron transfer and optical absorption of the photocatalyst. This type of fabrication strategy may be a new avenue for the synthesis of other ECNF-based ternary composites.

Effects of hydrothermal temperature on the morphology and photoelectrocatalytic performance of TiO2-based nanomaterials photoelectrode

2015 ◽  
Vol 08 (04) ◽  
pp. 1550034 ◽  
Author(s):  
Dong Li ◽  
Xiujuan Yu ◽  
Xiuwen Cheng
Keyword(s):  
Three Dimensional ◽  
Photogenerated Electron ◽  
Comparative Investigation ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Photoelectrochemical Performance ◽  
Electron Hole ◽  
Hydrothermal Temperature ◽  
Dimensional Network ◽  
Hole Recombination

TiO 2-based nanomaterials (BNMs) photoelectrode was successfully synthesized via a facile and controllable hydrothermal procedure. The as-prepared TiO 2-BNMs photoelectrode was characterized by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The resulting TiO 2-BNMs samples assembled by different morphologies were obtained through changing hydrothermal temperature that were: (i) One-dimensional (relative to nanosheets) nanobelts at 140°C, (ii) two-dimensional nanosheets at 160–180°C and (iii) three-dimensional network nanowires at 200–220°C. Structural investigation of the obtained nanomaterials revealed that the content of anatase increased as increasing the apparent dimensionality of the materials. The photoelectrochemical performance of TiO 2-BNMs photoelectrode was elucidated by comparative investigation on the electron transport and electron–hole (e-/h+) recombination in TiO 2-BNMs sample with typically morphology. The photoelectrochemical performance of the TiO 2-BNMs sample was obviously dependent on the morphology. Compared to the nanobelts and the network nanowires structure, the two-dimensional nanosheets displayed the more effective photogenerated electron transfer and reduced electron–hole recombination rate. Moreover, two-dimensional nanosheets had significantly enhanced photoelectrocatalytic efficiency for degradation of methyl orange (MO).

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