scholarly journals Intrinsic and Extrinsic Charge Transport in CH3NH3PbI3 Perovskites Predicted from First-Principles

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Tianqi Zhao ◽  
Wen Shi ◽  
Jinyang Xi ◽  
Dong Wang ◽  
Zhigang Shuai
Keyword(s):  
Charge Transport ◽  
Electron Mobility ◽  
First Principles ◽  
Phonon Scattering ◽  
Single Layer ◽  
Impurity Scattering ◽  
Hole Mobility ◽  
Single Layer Graphene ◽  
Device Structures ◽  
Charged Impurity Scattering

Abstract Both intrinsic and extrinsic charge transport properties of methylammonium lead triiodide perovskites are investigated from first-principles. The weak electron-phonon couplings are revealed, with the largest deformation potential (~ 5 eV) comparable to that of single layer graphene. The intrinsic mobility limited by the acoustic phonon scattering is as high as a few thousands cm2 V−1 s−1 with the hole mobility larger than the electron mobility. At the impurity density of 1018 cm−3, the charged impurity scattering starts to dominate and lowers the electron mobility to 101 cm2 V−1 s−1 and the hole mobility to 72.2 cm2 V−1 s−1. The high intrinsic mobility warrants the long and balanced diffusion length of charge carriers. With the control of impurities or defects as well as charge traps in these perovskites, enhanced efficiencies of solar cells with simplified device structures are promised.

Thermal Conductivity Reduction in Few-Layer Graphene

2011 ◽  
Author(s):  
Dhruv Singh ◽  
Jayathi Y. Murthy ◽  
Timothy S. Fisher
Keyword(s):  
Thermal Conductivity ◽  
Weak Coupling ◽  
Phonon Scattering ◽  
Single Layer ◽  
Acoustic Mode ◽  
Single Layer Graphene ◽  
Boltzmann Transport ◽  
Layer Graphene ◽  
Out Of Plane ◽  
Few Layer Graphene

Using the linearized Boltzmann transport equation and perturbation theory, we analyze the reduction in the intrinsic thermal conductivity of few-layer graphene sheets accounting for all possible three-phonon scattering events. Even with weak coupling between layers, a significant reduction in the thermal conductivity of the out-of-plane acoustic modes is apparent. The main effect of this weak coupling is to open many new three-phonon scattering channels that are otherwise absent in graphene. The highly restrictive selection rule that leads to a high thermal conductivity of ZA phonons in single-layer graphene is only weakly broken with the addition of multiple layers, and ZA phonons still dominate thermal conductivity. We also find that the decrease in thermal conductivity is mainly caused by decreased contributions of the higher-order overtones of the fundamental out-of-plane acoustic mode. Moreover, the extent of reduction is largest when going from single to bilayer graphene and saturates for four layers. The results compare remarkably well over the entire temperature range with measurements of of graphene and graphite.

Enhanced Vertical Charge Transport in a Semiconducting P3HT Thin Film on Single Layer Graphene

2014 ◽  
Vol 25 (5) ◽  
pp. 664-670 ◽  
Author(s):  
Vasyl Skrypnychuk ◽  
Nicolas Boulanger ◽  
Victor Yu ◽  
Michael Hilke ◽  
Stefan C. B. Mannsfeld ◽  
...  
Keyword(s):  
Thin Film ◽  
Charge Transport ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Layer Graphene

Electron Mobility Model for Tensile Strained-Si(101)

2014 ◽  
Vol 986-987 ◽  
pp. 131-135
Author(s):  
Jian An Wang ◽  
Meng Nan ◽  
Hui Yong Hu ◽  
He Ming Zhang
Keyword(s):  
Relaxation Time ◽  
Electron Mobility ◽  
Acoustic Phonon ◽  
Phonon Scattering ◽  
Impurity Scattering ◽  
Mobility Model ◽  
Strained Si ◽  
Average Momentum ◽  
Intervalley Scattering ◽  
Momentum Relaxation

Nowadays, the strained-Si technology has been used to maintain the momentum of semiconductor scaling due to its enhancement performance result from the higher mobility. In this paper, the influence of ionizing impurity scattering, acoustic phonon scattering and intervalley scattering to strained-Si (101) material is discussed.In addition, a calculation of the electron mobility in Strained-Si (101) material is made using the average momentum relaxation time method described in Ref [1]. The results show that the electron mobility increases gradually for both [001] and [100] orientations while for [010] orientation increases rapidly with the increasing Ge fraction x.[1]

Hole Mobility Calculation for Monolayer Molybdenum Tungsten Alloy Disulfide

2020 ◽  
Vol 20 (11) ◽  
pp. 7175-7180
Author(s):  
Ming-Ting Wu ◽  
Cheng-Hsien Yang ◽  
Yun-Fang Chung ◽  
Kuan-Ting Chen ◽  
Shu-Tong Chang
Keyword(s):  
First Principles ◽  
Single Layer ◽  
Hole Mobility ◽  
Higher Order ◽  
Tungsten Alloy ◽  
Band Model ◽  
First Principle ◽  
Approximation Model ◽  
Alloy Scattering ◽  
Mass Approximation

A simple band model using higher order non-parabolic effect was adopted for single layer molybdenum tungsten alloy disulfide (i.e., Mo1−xWxS2). The first-principles method considering 2 × 2 supercell was used to study band structure of single layer alloy Mo1−xWxS2 and a simple band (i.e., effective mass approximation model, EMA) model with higher order non-parabolic effect was used to fit the first-principle band structures in order to calculate corresponding the hole mobility. In addition, we investigate the alloy scattering effect on the hole mobility of Mo1−xWxS2.

scholarly journals Reduced crystallinity and enhanced charge transport by melt annealing of an organic semiconductor on single layer graphene

2016 ◽  
Vol 4 (19) ◽  
pp. 4143-4149 ◽  
Author(s):  
Vasyl Skrypnychuk ◽  
Nicolas Boulanger ◽  
Victor Yu ◽  
Michael Hilke ◽  
Michael F. Toney ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Charge Transport ◽  
Organic Semiconductor ◽  
Annealing Temperature ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Semiconducting Polymer ◽  
Layer Graphene ◽  
Melt Annealing

We report on the effect of the annealing temperature on the crystallization and the electrical properties of the semiconducting polymer poly(3-hexylthiophene) (P3HT) on single layer graphene.

First-Principles Study of 3D Transition Metal Doped Single-Layer Graphene

2020 ◽  
Vol 984 ◽  
pp. 82-87
Author(s):  
Bao Zhu Wang ◽  
Sheng Tang ◽  
Tong Wei ◽  
Jie Ren ◽  
Min Wang
Keyword(s):  
Fermi Level ◽  
First Principles ◽  
Density Functional ◽  
Single Layer ◽  
First Principles Calculation ◽  
Single Layer Graphene ◽  
Impurity Level ◽  
Layer System ◽  
Magnetic Ground State ◽  
Metal Doped

The electronic structure and magnetic properties of C atoms in Co, Ni-substituted graphene single-layers were studied by first-principles calculation method based on density functional theory. The study found that the pure graphene single-layer is an insulator, does not have magnetism, and we found that the doping of Co and Ni atoms alone does not make the system magnetic. Both Co and Ni atoms are capable of generating impurity levels in the graphene single-layer system. The impurity level of Co atom doping is 0.75 eV below the Fermi level, and the impurity level of Ni atom doping is 0.4 eV above the Fermi level. Studies on the coupling doping of Co and Ni atoms show that two different distance Co atoms or Ni atoms in the graphene single-layer are not always ferromagnetically coupled, and a stable magnetic ground state cannot be obtained. It can produce different magnetic ground states by controlling different doping distances, thus we provide one new way to control the spin properties.

p- and n-Type Charge Transport in Field-Effect Transistors of Pristine Poly(p-Phenylenevinylene)

2006 ◽  
Vol 965 ◽  
Author(s):  
Hiroshi Kayashima ◽  
Takeshi Yasuda ◽  
Katsuhiko Fujita ◽  
Tetsuo Tsutsui
Keyword(s):  
Thin Films ◽  
Charge Transport ◽  
Electron Mobility ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Hole Mobility ◽  
The Other ◽  
High Gravity ◽  
Gravity Condition ◽  
Calcium Source

ABSTRACTPoly(p-phenylenevinylene) (PPV) thin films were prepared by using drop casting under high gravity condition and p- and n-type PPV based field effect transistors (FET) have been fabricated. PPV FETs with gold source-drain electrodes showed the p-channel FET conduction. The FET characteristics of PPV were improved by annealing and the field-effect hole mobility was 8.8×10−4cm2V−1s−1. On the other hand, PPV FET with calcium source-drain electrodes showed the n-channel FET conduction and the field-effect electron mobility was 1.0×10−6cm2V−1s−1.

The Phonon Thermal Conductivity of a Single-Layer Graphene From Complete Phonon Dispersion Relations

2010 ◽  
Author(s):  
Yunfeng Gu ◽  
Zhonghua Ni ◽  
Minhua Chen ◽  
Kedong Bi ◽  
Yunfei Chen
Keyword(s):  
Thermal Conductivity ◽  
Acoustic Phonon ◽  
Phonon Scattering ◽  
Phonon Dispersion ◽  
Single Layer ◽  
Single Layer Graphene ◽  
Optical Phonons ◽  
Relaxation Rates ◽  
Phonon Thermal Conductivity ◽  
Transverse Acoustic

In this paper, the phonon scattering mechanisms of a single layer graphene are investigated based on the complete phonon dispersion relations. According to the selection rules that a phonon scattering process should obey the energy and momentum conservation conditions, the relaxation rates of combing and splitting Umklapp processes can be calculated by integrating the intersection lines between different phonon mode surfaces in the phonon dispersion relation space. The dependence of the relaxation rates on the wave vector directions is presented with a three dimensional surfaces over the first Brillion zone. It is found that the reason for the optical phonons contributing a little to heat transfer is attributed to the strong Umklapp processes but not to their low group velocities. The combing Umklapp scattering processes involved by the optical phonons mainly decrease the acoustic phonon thermal conductivity, while the splitting Umklapp scattering processes of the optical phonons mainly restrict heat conduction by the optical phonons themselves. Neglecting the splitting processes, the optical phonons can contribute more energy than that carried by the acoustic phonons. Based on the calculated phonon relaxation time, the thermal conductivities contributed from different mode phonons can be evaluated. At low temperatures, both longitudinal and in-plane transverse acoustic phonon thermal conductivities have T2 temperature dependence, and the out-of-plane transverse acoustic phonon thermal conductivity is proportion to T3/2. At room temperature, the calculated thermal conductivity is on the order of a few thousands W/m.K depending on the sample size and the edge roughness, which is in agreement with the recently measured data.

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