Extra long electron–hole diffusion lengths in CH3NH3PbI3−xClx perovskite single crystals

2017 ◽  
Vol 5 (33) ◽  
pp. 8431-8435 ◽  
Author(s):  
Fengying Zhang ◽  
Bin Yang ◽  
Yajuan Li ◽  
Weiqiao Deng ◽  
Rongxing He
Keyword(s):  
Single Crystals ◽  
Diffusion Length ◽  
Energy Levels ◽  
Trap State ◽  
Electron Hole ◽  
Carrier Transfer ◽  
State Densities

Both trap-state densities and energy levels affect carrier transfer, resulting in a maximum diffusion length of 380 μm in CH3NH3PbI3−xClx (x = 0.005).

scholarly journals Photoactive Tungsten-Oxide Nanomaterials for Water-Splitting

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1871
Author(s):  
Yerkin Shabdan ◽  
Aiymkul Markhabayeva ◽  
Nurlan Bakranov ◽  
Nurxat Nuraje
Keyword(s):  
Tungsten Oxide ◽  
Water Splitting ◽  
Diffusion Length ◽  
Photogenerated Electron ◽  
Photoelectrochemical Cell ◽  
High Electron ◽  
Applied Bias ◽  
Electron Hole ◽  
Research Directions ◽  
Photocatalytic Applications

This review focuses on tungsten oxide (WO3) and its nanocomposites as photoactive nanomaterials for photoelectrochemical cell (PEC) applications since it possesses exceptional properties such as photostability, high electron mobility (~12 cm2 V−1 s−1) and a long hole-diffusion length (~150 nm). Although WO3 has demonstrated oxygen-evolution capability in PEC, further increase of its PEC efficiency is limited by high recombination rate of photogenerated electron/hole carriers and slow charge transfer at the liquid–solid interface. To further increase the PEC efficiency of the WO3 photocatalyst, designing WO3 nanocomposites via surface–interface engineering and doping would be a great strategy to enhance the PEC performance via improving charge separation. This review starts with the basic principle of water-splitting and physical chemistry properties of WO3, that extends to various strategies to produce binary/ternary nanocomposites for PEC, particulate photocatalysts, Z-schemes and tandem-cell applications. The effect of PEC crystalline structure and nanomorphologies on efficiency are included. For both binary and ternary WO3 nanocomposite systems, the PEC performance under different conditions—including synthesis approaches, various electrolytes, morphologies and applied bias—are summarized. At the end of the review, a conclusion and outlook section concluded the WO3 photocatalyst-based system with an overview of WO3 and their nanocomposites for photocatalytic applications and provided the readers with potential research directions.

Diffusion Length in n-Doped 4H Silicon Carbide Crystals Detected by Alpha Particle Probe

2009 ◽  
Vol 615-617 ◽  
pp. 857-860
Author(s):  
Donatella Puglisi ◽  
Gaetano Foti ◽  
Giuseppe Bertuccio
Keyword(s):  
Silicon Carbide ◽  
Doping Concentration ◽  
Diffusion Length ◽  
Schottky Diodes ◽  
Radiation Detectors ◽  
Electron Hole ◽  
Active Volume ◽  
Particle Detectors ◽  
Electron Hole Pair ◽  
Nuclear Detectors

The achievement of nuclear detectors in Silicon Carbide imposes severe constraints on the electronic quality and thickness of the material due to the relatively high value of the energy required to generate an electron-hole pair (7.8 eV) in this material compared to the value for Si (3.6 eV). In this work, 4H-SiC charged particle detectors were realised using epitaxial layers of n-type doping as active region. The thickness of the epilayer is always below 80 μm with a net doping concentration in the range of 8 x 1013 to 1016 cm-3. These properties allowed the fabrication of Schottky diodes that operate well as radiation detectors. At low doping concentration, the epilayer is totally depleted at quite low reverse bias (≈ 50 V), thereby obtaining the maximum active volume.

Crystal Growth and Ferroelectric Properties of Superlattice-Structured Bi4Ti3O12-PbBi4Ti4O15 Single Crystals

2008 ◽  
Vol 388 ◽  
pp. 237-240
Author(s):  
Mariko Ikezaki ◽  
Yuji Noguchi ◽  
Keiichi Katayama ◽  
Masaru Miyayama
Keyword(s):  
Crystal Growth ◽  
Single Crystals ◽  
Leakage Current ◽  
Room Temperature ◽  
Remanent Polarization ◽  
Marked Decrease ◽  
Ferroelectric Properties ◽  
Electron Hole ◽  
N2 Atmosphere ◽  
Saturated Polarization

Superlattice-structured Bi4Ti3O12- PbBi4Ti4O15 single crystals were grown, and their properties of polarization hysteresis and leakage current along the a axis were investigated. Oxidation annealing led to a marked increase in leakage current, while annealing in N2 atmosphere yielded a marked decrease in leakage current at room temperature. These results show that electron hole is the dominant carrier for the leakage current. A well-saturated polarization hysteresis with a remanent polarization of 41 μC/cm2 was observed, which is suggested to originate from the peculiar ferroelectric displacement of Bi in the Bi2O2 layers.

Analysis of trap state densities at HfO2/In0.53Ga0.47As interfaces

2010 ◽  
Vol 96 (10) ◽  
pp. 102910 ◽  
Author(s):  
Yoontae Hwang ◽  
Roman Engel-Herbert ◽  
Nicholas G. Rudawski ◽  
Susanne Stemmer
Keyword(s):  
Trap State ◽  
State Densities

Study on the Absorption Spectra of Ga2Se3:Co2+ Single Crystals

2009 ◽  
Vol 64 (12) ◽  
pp. 834-836
Author(s):  
Chao Ni ◽  
Yi Huang ◽  
Maolu Du
Keyword(s):  
Experimental Data ◽  
Fine Structure ◽  
Bond Length ◽  
Single Crystals ◽  
Crystal Field ◽  
Energy Levels ◽  
Crystal Field Parameter ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Cubic Crystal

Introducing the average covalent factor N and considering the interaction of the cubic crystal field, the spin-orbit coupling and Tree’s correction effects, the crystal field parameter Dq was calculated. Also the varying tendency of Dq with the bond length R was investigated. Using the complete diagonalizing method the energy levels of the fine structure of Ga2Se3:Co2+ single crystal were calculated and assigned. The calculated and assigned results are consistent with the experimental data

Colour centres in zircon containing both Eu3+ and U4+ ions

1970 ◽  
Vol 23 (8) ◽  
pp. 1513 ◽  
Author(s):  
PE Fielding
Keyword(s):  
Experimental Data ◽  
Single Crystals ◽  
Absorption Spectra ◽  
Electron Energy ◽  
Energy Levels ◽  
Alkali Halides ◽  
Colour Centres

Single crystals of zircon containing both Eu3+ and U4+ were grown from flux melts cooled at rates varying between 4�/hr and 2�/hr. Irradiation with u.v. develops colour centres only in those regions of a crystal containing Eu3+ and U4+. Fluorescence and absorption spectra measured at temperatures down to 77�K show that these centres are similar in behaviour to F and F' centres in the alkali halides. They are thought to be related to an exchange coupled pair, U4+-02-Eu3+, but the experimental data permit only a description in terms of one-electron energy levels. The same basic behaviour is observed for zircon containing U4+ and any other lanthanide but some interesting differences are described for U4+, Dy3+.

scholarly journals GQD/Bi2O3 Composite for high-efficient photocatalysts

2020 ◽  
Vol 213 ◽  
pp. 02037
Author(s):  
Chengli Tang ◽  
Limei Zhang
Keyword(s):  
Visible Light ◽  
Active Sites ◽  
Minority Carrier ◽  
Diffusion Length ◽  
Graphene Quantum Dots ◽  
Photocatalytic Efficiency ◽  
Electron Hole ◽  
Minority Carrier Diffusion Length ◽  
High Efficient ◽  
Visible Light Photocatalytic

Bismuth oxide (Bi2O3) is one of the potential visible-light photocatalytic materials, however, due to low electron mobility and short minority carrier diffusion length, the photocatalytic activity of Bi2O3 is restricted. The GQD/Bi2O3 composites were synthesized stably depositing single-crystalline graphene quantum dots (GQDs) with absorption edge at ~10nm, prepared by using a top-down method. The GQDBi2O3 heterojunctions were successfully established, the photo-generated electrons transfer from the Bi2O3 to the GQDs at the interface of the GQD-Bi2O3 heterojunctions, result in efficient electron-hole pairs separation and higher photocatalytic efficiency. The optimum visible performance is achieved at GQD content of 1.0 wt %, the RhB dye was nearly completely decoloured after 90 min of visible-light irradiation, and then decrease at higher doping levels due to the thicker GQD layer will cover the active sites of Bi2O3, thus leading to the greatly reduced catalytic activity.

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