scholarly journals Layer-resolved ultrafast extreme ultraviolet measurement of hole transport in a Ni-TiO2-Si photoanode

2020 ◽  
Vol 6 (14) ◽  
pp. eaay6650 ◽  
Author(s):  
Scott K. Cushing ◽  
Ilana J. Porter ◽  
Bethany R. de Roulet ◽  
Angela Lee ◽  
Brett M. Marsh ◽  
...  
Keyword(s):  
Carrier Transport ◽  
Extreme Ultraviolet ◽  
Diffusion Constant ◽  
Hole Mobility ◽  
Hole Transport ◽  
Oxide Semiconductor ◽  
Electron Hole ◽  
Spectral Shifts ◽  
Transient Spectra ◽  
Recombination Kinetics

Metal oxide semiconductor junctions are central to most electronic and optoelectronic devices, but ultrafast measurements of carrier transport have been limited to device-average measurements. Here, charge transport and recombination kinetics in each layer of a Ni-TiO2-Si junction is measured using the element specificity of broadband extreme ultraviolet (XUV) ultrafast pulses. After silicon photoexcitation, holes are inferred to transport from Si to Ni ballistically in ~100 fs, resulting in characteristic spectral shifts in the XUV edges. Meanwhile, the electrons remain on Si. After picoseconds, the transient hole population on Ni is observed to back-diffuse through the TiO2, shifting the Ti spectrum to a higher oxidation state, followed by electron-hole recombination at the Si-TiO2 interface and in the Si bulk. Electrical properties, such as the hole diffusion constant in TiO2 and the initial hole mobility in Si, are fit from these transient spectra and match well with values reported previously.

Hole Transport in Self-Organized Oligosilane Thin Films with Highly Ordered Hopping Sites

2001 ◽  
Vol 707 ◽  
Author(s):  
H. Okumoto ◽  
T. Yatabe ◽  
A. Richter ◽  
M. Shimomura ◽  
A. Kaito ◽  
...  
Keyword(s):  
Thin Films ◽  
Transport Properties ◽  
Carrier Transport ◽  
Hole Mobility ◽  
Multilayered Structure ◽  
Hole Transport ◽  
Conjugated Molecules ◽  
Disordered Structures ◽  
Self Organized ◽  
Carrier Transport Properties

ABSTRACTSelf-organized oligosilane thin films possess molecular orientation normal to substrates with multilayered structure. This unique order of σ-conjugated molecules results in good hole transport properties. In the present work, carrier transport properties at low temperature are studied for 1,10-diethyldecamethylsilane polycrystalline films. Even at a temperature as low as 173 K, a time-of-flight transient photocurrent waveform showed a clear plateau and a sharp decay, whose shape is similar to that at room temperature. Their hole mobility followed Arrhe-nius type temperature dependence with a small activation energy of 0.09 eV. The hole mobility of 6.3×10-5cm-2/Vs at 193 K was more than 2 orders of magnitude higher than that of typical polysilanes, which inevitably contain disordered structures hindering smooth carrier transport.

Hole Transport In Self-Organized Oligosilane Thin Films With Highly Ordered Hopping Sites

2001 ◽  
Vol 708 ◽  
Author(s):  
H. Okumoto ◽  
T. Yatabe ◽  
A. Richter ◽  
M. Shimomura ◽  
A. Kaito ◽  
...  
Keyword(s):  
Thin Films ◽  
Transport Properties ◽  
Carrier Transport ◽  
Hole Mobility ◽  
Multilayered Structure ◽  
Hole Transport ◽  
Conjugated Molecules ◽  
Disordered Structures ◽  
Self Organized ◽  
Carrier Transport Properties

ABSTRACTSelf-organized oligosilane thin films possess molecular orientation normal to substrates with multilayered structure. This unique order of -conjugated molecules results in good hole transport properties. In the present work, carrier transport properties at low temperature are studied for 1,10-diethyldecamethylsilane polycrystalline films. Even at a temperature as low as 173 K, a time-of-flight transient photocurrent waveform showed a clear plateau and a sharp decay, whose shape is similar to that at room temperature. Their hole mobility followed Arrhenius type temperature dependence with a small activation energy of 0.09 eV. The hole mobility of 6.3×10-5cm2/Vs at 193 K was more than 2 orders of magnitude higher than that of typical polysilanes, which inevitably contain disordered structures hindering smooth carrier transport.

Carrier Transport Enhancement in Bulk-Heterojunction Organic Photovoltaics with Boron or Nitrogen-Doped Carbon Nanotubes

2012 ◽  
Vol 229-231 ◽  
pp. 267-270 ◽  
Author(s):  
Hyung Il Park ◽  
Ju Min Lee ◽  
Ji Sun Park ◽  
Kyung Eun Lee ◽  
Sang Ouk Kim
Keyword(s):  
Carbon Nanotubes ◽  
Active Layer ◽  
Organic Solar Cells ◽  
Carrier Transport ◽  
Bulk Heterojunction ◽  
Hole Transport ◽  
Electron Hole ◽  
Transport Enhancement ◽  
Nitrogen Doped Carbon ◽  
Walled Cnts

We present the remarkable performance improvement of organic solar cells upon incorporating N- or B-doped carbon nanotubes (CNTs) into the organic semiconductor active layer. A small amount (0.2-5.0 wt%) of doped multi-walled CNTs are added to the bulk-heterojuction of poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl) propyl-1-phenyl[6,6]C61 (PCBM). Unlike undoped metallic multi-walled CNTs, which cause undesired electron-hole recombination, N- or B-doped CNTs uniformly dispersed in the active layer selectively enhance electron or hole transport, respectively, and eventually help carrier collection. Specifically, the incorporation of 1.0 wt% B-doped CNTs results in a balanced electron and hole transport and accomplishes a power conversion efficiency improvement from 3.0 % (conventional control cells without CNTs) to 4.1 %.

scholarly journals Research progress of nanoarray structure transport layers in perovskite solar cells

2021 ◽  
Vol 4 (2) ◽  
Author(s):  
Fangxin Tan ◽  
Shan Cong ◽  
Qinghua Yi ◽  
Zhida Han ◽  
Yushen Liu
Keyword(s):  
Solar Cells ◽  
Carrier Transport ◽  
Crack Nucleation ◽  
Perovskite Solar Cells ◽  
Hole Transport ◽  
Transport Layer ◽  
Research Progress ◽  
Hole Transport Layer ◽  
Electron Hole ◽  
Improve Device

The electron/hole transport layer can promote charge transfer and improve device performance, which is used in perovskite solar cells. The nanoarray structure transport layers can not only further promote carrier transport but also reduce recombination. It also has a great potential in enhancing perovskite light absorption, improving device stability and inhibiting the crack nucleation of different structure layers in perovskite solar cells. This paper reviewed the research progress of perovskite solar cells with different nanoarray structure transport layers. The challenges and development directions of perovskite solar cells based on nanoarray structure transport layers are also summarized and prospected. 

scholarly journals Charge Sharing and Charge Loss in High-Flux Capable Pixelated CdZnTe Detectors

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 3260
Author(s):  
Kjell A. L. Koch-Mehrin ◽  
Sarah L. Bugby ◽  
John E. Lees ◽  
Matthew C. Veale ◽  
Matthew D. Wilson
Keyword(s):  
Carrier Transport ◽  
Hole Transport ◽  
Uniform Electric Field ◽  
Photon Flux ◽  
High Flux ◽  
Charge Sharing ◽  
Cdte Detector ◽  
Charge Loss ◽  
Cdznte Detectors ◽  
Detector Model

Cadmium zinc telluride (CdZnTe) detectors are known to suffer from polarization effects under high photon flux due to poor hole transport in the crystal material. This has led to the development of a high-flux capable CdZnTe material (HF-CdZnTe). Detectors with the HF-CdZnTe material have shown promising results at mitigating the onset of the polarization phenomenon, likely linked to improved crystal quality and hole carrier transport. Better hole transport will have an impact on charge collection, particularly in pixelated detector designs and thick sensors (>1 mm). In this paper, the presence of charge sharing and the magnitude of charge loss were calculated for a 2 mm thick pixelated HF-CdZnTe detector with 250 μm pixel pitch and 25 μm pixel gaps, bonded to the STFC HEXITEC ASIC. Results are compared with a CdTe detector as a reference point and supported with simulations from a Monte-Carlo detector model. Charge sharing events showed minimal charge loss in the HF-CdZnTe, resulting in a spectral resolution of 1.63 ± 0.08 keV Full Width at Half Maximum (FWHM) for bipixel charge sharing events at 59.5 keV. Depth of interaction effects were shown to influence charge loss in shared events. The performance is discussed in relation to the improved hole transport of HF-CdZnTe and comparison with simulated results provided evidence of a uniform electric field.

Time-resolved Photoconductivity as a Probe of Carrier Transport in Microcrystalline Silicon

2006 ◽  
Vol 910 ◽  
Author(s):  
Steve Reynolds
Keyword(s):  
Density Of States ◽  
Carrier Mobility ◽  
Carrier Transport ◽  
Film Growth ◽  
Hole Mobility ◽  
Transport Parameters ◽  
Microcrystalline Silicon ◽  
Time Resolved ◽  
Transient Photoconductivity ◽  
Transport Measurements

AbstractThe use of transient photoconductivity techniques in the investigation of carrier transport in microcrystalline silicon is described. Results are presented which highlight variations in transport parameters such as carrier mobility and density of states with structure composition. Hole mobility is significantly enhanced by crystalline content in the film of 10% or less. The density of states inferred from transport measurements parallel to and at right angles to the direction of film growth differ somewhat, suggesting that transport may be anisotropic.

Characteristic lengths for three-carrier transport with spin-flip and electron-hole recombination

2016 ◽  
Vol 93 (19) ◽  
Author(s):  
Maja Krcmar ◽  
Wayne M. Saslow
Keyword(s):  
Carrier Transport ◽  
Electron Hole ◽  
Spin Flip ◽  
Hole Recombination

Modeling the Effect of Annealing and Regioregularity on Electron and Hole Transport Characteristics of Bulk Heterojunction Organic Photovoltaic Devices

2010 ◽  
Vol 1270 ◽  
Author(s):  
Shabnam Shambayati ◽  
Bobak Gholamkhass ◽  
Soheil Ebadian ◽  
Steven Holdcroft ◽  
Peyman Servati
Keyword(s):  
Annealing Time ◽  
Electron Mobility ◽  
Bulk Heterojunction ◽  
Acid Methyl Ester ◽  
Hole Mobility ◽  
Phase Segregation ◽  
Hole Transport ◽  
Trap States ◽  
Current Voltage ◽  
Steep Decline

AbstractIn this study, the dark current-voltage characteristics of electron-only and hole-only poly(3-hexyl thiophene) (P3HT):[6,6]-phenyl C61-butyric acid methyl ester (PCBM) as a function of regioregularity (RR) and annealing time is investigated using the mobility edge (ME) model. This model is used to analyze the degradation of electron and hole mobilities as a function of annealing time for 93%-RR and 98%-RR P3HT:PCBM devices. The hole mobility is almost unchanged by the RR nature of P3HT and thermal annealing. The electron mobility, however, behaves differently after annealing. The electron mobility of 98%-RR devices, which is initially higher than that of the 93%-RR devices, experiences a steep decline with annealing. Based on ME analysis, this is due to an increase in trap states in the exponential tail caused by phase segregation of solid state blends of 98%-RR polymer and PCBM. The electron mobility of 93%-RR devices increases with annealing due to an optimization of nano-phase separated morphology.

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