共查询到20条相似文献,搜索用时 15 毫秒
1.
Importance of PbI_2 morphology in two-step deposition of CH_3NH_3PbI_3 for high-performance perovskite solar cells
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Controlling the morphology of the perovskite film is an effective way to improve the photoelectric conversion efficiency of solar cell devices. In this work, we study the influence of the crystallization condition on PbI_2 morphology and the performances of resulting perovskite solar cells. The PbI_2 morphologies and coverage rates under different formation conditions such as solvent effect, slow crystallization at room temperature and substrate-preheating, are found to be of crucial importance for preparing high-quality perovskite. The generation of loosely packed disk-like PbI_2 film with interpenetrating nanopores promotes the penetration of methyl ammonium iodide(MAI), leading to a better crystallinity of the perovskite film, and a best repeatable power conversion efficiency of 11.59% is achieved when methyl ammonium lead triiodide(CH_3NH_3PbI_3, MAPbI_3) is employed. In addition, an excellent device is also obtained with an efficiency of more than 93% to remain after working for 43 days. 相似文献
2.
3.
First-principles hybrid functional study of the electronic structure and charge carrier mobility in perovskite CH_3NH_3SnI_3
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We calculate the electronic properties and carrier mobility of perovskite CH_3NH_3SnI_3 as a solar cell absorber by using the hybrid functional method. The calculated result shows that the electron and hole mobilities have anisotropies with a large magnitude of 1.4 × 10~4cm~2·V~(-1)·s~(-1) along the y direction. In view of the huge difference between hole and electron mobilities, the perovskite CH3NH3 Sn I3can be considered as a p-type semiconductor. We also discover a relationship between the effective mass anisotropy and electronic occupation anisotropy. The above results can provide reliable guidance for its experimental applications in electronics and optoelectronics. 相似文献
4.
Manuel Souto Dayana C. Morales Judith Guasch Imma Ratera Concepció Rovira Anna Painelli Jaume Veciana 《Journal of Physical Organic Chemistry》2014,27(6):465-469
A comparative analysis of the physicochemical properties of different donor–acceptor dyads, based on a perchlorotriphenylmethyl radical acceptor subunit linked through a vinylene π‐bridge to ferrocene derivatives (1–3) or a tetrathiafulvalene (4) donor subunit, is presented. Intramolecular electron transfer and charge delocalization of these donor–acceptor dyads are discussed on the basis of data obtained in solution by cyclic voltammetry, UV–Vis near‐infrared, and electron spin resonance spectroscopies. Bistability in the crystalline phase is also discussed on the basis of the results provided by X‐ray diffraction analysis and temperature‐dependent Mössbauer spectra. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
5.
Ultrafast proton transfer dynamics of 2-(2'-hydroxyphenyl)benzoxazole dye in different solvents
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The excited-state intramolecular proton transfer of 2-(2-hydroxyphenyl)benzoxazole dye in different solvents is investigated using ultrafast femtosecond transient absorption spectroscopy combined with quantum chemical calculations.Conformational conversion from the syn-enol configuration to the keto configuration is proposed as the mechanism of excited-state intramolecular proton transfer.The duration of excited-state intramolecular proton transfer is measured to range from 50 fs to 200 fs in different solvents.This time is strongly dependent on the calculated energy gap between the N-S;and T-S;structures in the S;state.Along the proton transfer reaction coordinate,the vibrational relaxation process on the S;state potential surface is observed.The duration of the vibrational relaxation process is determined to be from8.7 ps to 35 ps dependent on the excess vibrational energy. 相似文献
6.
采用位置灵敏探测和飞行时间技术研究了高电荷态Xe离子(q=15,17,19,21,23)与He原子碰撞中双电子转移截面与单电子转移截面比随入射离子电荷态的变化规律.提出一步过程假定,对扩展的经典过垒(ECB)模型进行了修正,利用修正模型计算得到的单、双电子转移绝对截面与Andersson等人和Selberg等人的实验结果很好符合,所得截面比与本实验得到的双电子转移截面与单电子俘获截面比较好符合.
关键词:
离子 原子碰撞
电荷转移
一步过程 相似文献
7.
Photo-induced intramolecular electron transfer and intramolecular vibrational relaxation of rhodamine 6G in DMSO revealed by multiplex transient grating spectroscopy
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Photo-induced intramolecular electron transfer (PIET) and intramolecular vibrational relaxation (IVR) dynamics of the excited state of rhodamine 6G (Rh6G+) in DMSO are investigated by multiplex transient grating. Two major compo- nents are resolved in the dynamics of Rh6G+. The first component, with a lifetime τTPIET = 140 fs-260 fs, is attributed to PIET from the phenyl ring to the xanthene plane. The IVR process occurring in the range ZIVR = 3.3 ps-5.2 ps is much slower than the first component. The PIET and IVR processes occurring in the excited state of Rh6G+ are quantitatively determined, and a better understanding of the relationship between these processes is obtained. 相似文献
8.
A switch in the electron transfer from heme a to binuclear centre of cytochrome c oxidase 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
New experimental evidence that a switch controls the reduction of the heme a3-CuB binuclear centre has been observed in the N2-dried thin film of purified cytochrome oxidase. When immersing the enzyme film into the acid phosphate buffer with extremely low concentration of dithionite, a spectrum was given to show a reduction of heme a with no electrons resting on CuA. By increasing dithionite, electrons could be accumulated gradually on CuA, but the binuclear centre still remains in the oxidized state. When the accumulation of electrons on CuA and/or heme a exceeded a threshold, a turnover of reduction of the binuclear centre and oxidation of heme a occurred abruptly. This switch-like action is pH-dependent. 相似文献
9.
Kinetics study of ultrafast electron transfer from sensitized dyes to silver halide microcrystals 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Spectral sensitization micromechanism of cyanine dyes J-aggregate adsorbed
on the tabular and cubic AgBr microcrystals with different dye
concentrations
is studied by using picosecond time-resolved fluorescence spectroscopy, and
the dependences of electron transfer and spectral efficiency sensitization
on different conditions are analysed in detail. With the steady
spectroscopy, the wavelengths of absorption and fluorescence of J-aggregate
adsorbed on AgBr microcrystals are found to shift to red relative to dye
monomer. The spectrum of fluorescence has a red shift relative to the
absorption peak. With the time-resolved fluorescence spectroscopy, the
fluorescence decay curves of cyanine dyes J-aggregate adsorbed on the
tabular and cubic AgBr grains are found to be fitted well by a
double-exponential decay function. The fitting curves consist of a fast and
a slow component. Because of the large amplitude of the fast component, this
fast decay should be attributable mainly to the electron transfer from
J-aggregate of dye to a conduction band of AgBr. 相似文献
10.
Recently, the quasi-two-dimensional electron gas (q2DEG) confined at the interface between LaAlO3 and SrTiO3 has attracted significant attention. In this paper, we briefly review experimental methods that have been used to tune the carrier density and mobility of this q2DEG. These methods can be classified into two categories: growth-related tuning (i.e. substrate, growth temperature, oxygen pressure, post-annealing, LaAlO3 thickness, stoichiometry, and capping layers) and post-growth tuning (i.e. electrostatic field gating, conductive atomic force microscopy and surface adsorbates). Taken together, these methods enable the broad tuning of the electronic properties of this interface. 相似文献
11.
Dejan M. Gvozdi Jovan B. Radunovi 《International Journal of Infrared and Millimeter Waves》1996,17(6):1001-1009
This paper analyses the influence of nonstationary effects on response pulswidth of Metal-Semiconductor-Metal Photodetector (MSM-PD) made of a two-valley semiconductor. A phenomenological model is used for 2D numerical simulation of carrier transport and intervalley transfer. The analysis of the pulsewidth response of the MSM-PD has been made for various micron and submicron structures, bias voltages and incident light wavelengths. 相似文献
12.
A. Yu. Kobitski G. Salvan R. Scholz D. Tenne T. U. Kampen H. P. Wagner D. R. T. Zahn 《Applied Surface Science》2002,190(1-4):386-389
In the present work, we investigate the vibrational properties of a PTCDA molecule with an additional positive or negative charge using density functional theory. With respect to the calculated vibrational frequencies of the neutral molecule, some modes in particular in the region 1200–1800 cm−1 show large shifts. These calculations are compared with resonant Raman spectra of sub-monolayer PTCDA films on passivated semiconductor surfaces, both before and after annealing the deposited films at elevated temperatures (350 °C). Independent of the sample treatment, the sub-monolayer Raman spectra correspond quite well to reference spectra obtained for thicker films, and we find no evidence for the strong shifts predicted in the calculations for the charged species. From the small changes in the mode frequencies it can be concluded that any charge transfer present involves significantly less than one elementary charge. 相似文献
13.
A quantum-chemical calculation of the excited electronic states of a Rh. Sphaeroides reaction centre was performed. We discovered a new excited electronic state which can participate in electron transfer (ET). The energy gradient calculations showed that photoexcitation activates only high-frequency vibrational modes. This contradicts the widely accepted picture of ET resulting from vibrational wave packet motion. An alternative model is suggested where ET has a purely dissipative character and occurs only due to pigment--protein interaction. With this model, we demonstrate that oscillations in the femtosecond spectra can be caused by the new electronic state and non-Markovian character of dissipative dynamics. 相似文献
14.
15.
主要介绍了飞秒电子衍射系统的组成及设计指标. 包括光电阴极、电子聚焦系统、电子偏转系统、双微通道板(MCP)电子探测器等,并给出了基本的设计思路、设计结果. 光电阴极是由位于蓝宝石晶体上面的银膜构成,为了获得足够小的电子束斑以及减小电子上靶时的角度,紧贴栅极后放置一个100μm的小孔,对电子束的形状和大小进行限制. 采用磁电子透镜进行聚焦,电子衍射图样由放置在样品后面的双MCP像增强器进行探测. 在设计计算时,用Monte Carlo方法对光电子的初能量、初角度以及初位置分布进行抽样,用有限元法计算磁透镜
关键词:
飞秒电子枪
有限元法
Monte Carlo模拟
调制传递函数 相似文献
16.
17.
Complexation of bis‐crown stilbene with alkali and alkaline‐earth metal cations. Ultrafast excited state dynamics of the stilbene‐viologen analogue charge transfer complex
下载免费PDF全文
![点击此处可从《Journal of Physical Organic Chemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Valery V. Volchkov Mikhail V. Rusalov Fedor E. Gostev Ivan V. Shelaev Viktor A. Nadtochenko Artem I. Vedernikov Asya A. Efremova Lyudmila G. Kuz'mina Sergey P. Gromov Michael V. Alfimov Mikhail Ya. Melnikov 《Journal of Physical Organic Chemistry》2018,31(2)
The complex formation of bis(18‐crown‐6)stilbene ( 1 ) and its supramolecular donor‐acceptor complex with N,N′‐bis(ammonioethyl) 1,2‐di(4‐pyridyl)ethylene derivative ( 2 ) with alkali and alkaline‐earth metal perchlorates has been studied using absorption, steady‐state fluorescence, and femtosecond transient absorption spectroscopy. The formation of 1 ?Mn+ and 1 ?(Mn+)2 complexes in acetonitrile was demonstrated. The weak long‐wavelength charge‐transfer absorption band of 1 · 2 completely vanishes upon complexation with metal cations because of disruption of the pseudocyclic structure. The spectroscopic and luminescence parameters, stability constants, and 2‐stage dissociation constants were calculated. The initial stage of a recoordination process was found in the excited complexes 1 ?M+ and 1 ?(M+)2 (M = Li, Na). The pronounced fluorescence quenching of 1 · 2 is explained by very fast back electron transfer (τet = 0.397 ps). The structure of complex 1 · 2 was studied by X‐ray diffraction; stacked ( 1 · 2 )m polymer in which the components were connected by hydrogen bonding and stacking was found in the crystal. These compounds can be considered as novel optical molecular sensors for alkali and alkaline‐earth metal cations. 相似文献
18.
Santiago Martín 《Surface science》2006,600(15):3045-3051
Positively ionized monolayers of a viologen derivative, namely 1,1′-dioctadecyl-4,4′-bipyridilium (C18V2+), were prepared onto aqueous solutions of a tetracyanoquinodimethanide salt, , where the tetracyanoquinodimethanide anions are in a mixed valence state. UV-vis reflection spectroscopy has been used for proving in situ the incorporation of tetracyanoquinodimethanide anions into the viologen monolayer. The UV-vis spectra clearly show the presence of a band in the 550-850 nm region that is not visible in viologen monolayers fabricated onto a pure water subphase. Moreover, a charge-transfer interaction between the two molecules occurs at the air-water interface. A simultaneous quantitative analysis of the two active molecules in the UV-vis region has facilitated the investigation of the viologen tetracyanoquinodimethanide hybrid monolayers. An organization model at the air-water interface consistent with the reflection spectroscopy data has been proposed where a parallel arrangement of the viologen dications and anions is assumed. The ratio of the two materials in the monolayer was also determined and resulted to be , i.e. stoichiometry of charges. This ratio decreases after a noticeable kink in the π-A isotherm, and has been interpreted as a reorganization of the molecules in the monolayer leading to an ejection of some ions from the interface to the subphase, probably due to steric hindrance. 相似文献
19.
A method is described for the quantification of the sp2, sp3 and intermediate hybridizations in several carbon (C) material samples. Electron energy-loss near-edge spectra were acquired using fast electrons (120 keV) in an electron microscope in nanobeam configuration under the so-called ”magic-angle” condition, and were analysed to extract the sp2 and sp3 fractions, and identify the possible mixed sp2+ε hybridizations. The method consists in projecting the unknown spectra on a basis made up of pure sp2 and sp3 spectra, obtained under the same experimental conditions from graphite and diamond crystals, respectively. The residual spectra contain information about the intermediate hybridizations sp2+ε occurring in the samples. The method was successfully tested on “ab initio” numerically generated spectra relative to amorphous C materials. Finally, it was applied to actual C amorphous and pyrolytic samples, and results were compared to those obtained by the most commonly used, conventional ”three-Gaussian” method. The combined application of electron diffraction and spectroscopy, in the nanobeam configuration, yielded useful information about the atomic and electronic structure from very small volumes of the unknown C material. 相似文献
20.
Rmulo A. Ando Deborah R. C. Matazo Paulo S. Santos 《Journal of Raman spectroscopy : JRS》2010,41(7):771-775
Although the amine sulfur dioxide chemistry was well characterized in the past both experimentally and theoretically, no systematic Raman spectroscopic study describes the interaction between N,N‐dimethylaniline (DMA) and sulfur dioxide (SO2). The formation of a deep red oil by the reaction of SO2 with DMA is an evidence of the charge transfer (CT) nature of the DMA–SO2 interaction. The DMA–SO2 normal Raman spectrum shows the appearance of two intense bands at 1110 and 1151 cm−1, which are enhanced when resonance is approached. These bands are assigned to νs(SO2) and ν(ϕ N) vibrational modes, respectively, confirming the interaction between SO2 and the amine via the nitrogen atom. The dimethyl group steric effect favors the interaction of SO2 with the ring π electrons, which gives rise to a π–π* low‐energy CT electronic transition, as confirmed by time‐dependent density functional theory (TDDFT) calculations. In addition, the calculated Raman DMA–SO2 spectrum at the B3LYP/6‐311 + + g(3df,3pd) level shows good agreement with the experimental results (vibrational wavenumbers and relative intensities), allowing a complete assignment of the vibrational modes. A better understanding of the intermolecular interactions in this model system can be extremely useful in designing new materials to absorb, detect, or even quantify SO2. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献