scholarly journals Manipulating the interlayer carrier diffusion and extraction process in organic-inorganic heterojunctions: from 2D to 3D structures

2022 ◽  
Vol 6 (1) ◽  
Author(s):  
Jia-Wei Qiao ◽  
Wen-Qing Zhang ◽  
Feng-Zhe Cui ◽  
Hang Yin ◽  
Lin Feng ◽  
...  
Keyword(s):  
Diffusion Process ◽  
Transfer Rate ◽  
Extraction Efficiency ◽  
Critical Role ◽  
Band Alignment ◽  
Organic Layer ◽  
Carrier Diffusion ◽  
Carrier Transfer ◽  
Transfer Behavior ◽  
Carrier Extraction

AbstractInterlayer carrier transfer at heterointerfaces plays a critical role in light to electricity conversion using organic and nanostructured materials. However, how interlayer carrier extraction at these interfaces is poorly understood, especially in organic-inorganic heterogeneous systems. Here, we provide a direct strategy for manipulating the interlayer carrier diffusion process, transfer rate and extraction efficiency in tetracene/MoS2 type-II band alignment heterostructure by constructing the 2D–3D organic-inorganic (O-I) system. As a result, the prolonged diffusion length (12.32 nm), enhanced electron transfer rate (9.53 × 109 s−1) and improved carrier extraction efficiency (60.9%) are obtained in the 2D O-I structure which may be due to the more sufficient charge transfer (CT) state generation. In addition, we have demonstrated that the interlayer carrier transfer behavior complied with the diffusion mechanism based on the one-dimensional diffusion model. The diffusion coefficients have varied from 0.0027 to 0.0036 cm2 s−1 as the organic layer changes from 3D to 2D structures. Apart from the relationship between the carrier injection and diffusion process, temperature-dependent time-resolved spectra measurement is used to reveal the trap-related recombination that may limit the interlayer carrier extraction. The controllable interlayer carrier transfer behavior enables O-I heterojunction to be optimized for optoelectronic applications.

Charge Transfer from PbS Quantum Dots to Insulating TiO2 Matrix

1995 ◽  
Vol 382 ◽  
Author(s):  
R. Könenkamp ◽  
P. Hoyer
Keyword(s):  
Conduction Band ◽  
Quantum Confinement ◽  
Visible Spectrum ◽  
Spatial Separation ◽  
Band Alignment ◽  
Band Edge ◽  
Conduction Band Edge ◽  
Carrier Transfer ◽  
Quantum Size ◽  
Pbs Quantum Dots

ABSTRACTWe report on the photoconductivity of thin films consisting of a porous nanocrystalline TiO2 matrix and quantum size PbS clusters adsorbed on the inner surfaces of theTiO2. The PbS clusters are typically a few nm in size and are not connected. Due to quantum confinement the bandgap of the clusters is widened to around 2 eV from the 0.41 eV value for PbS bulk. The clusters thus absorb in the visible spectrum. However, due to their spatial separation, photoconductance through the film requires carrier transfer through the TiO2 matrix. Our data show this to occur only for clusters <25 Å, for which the conduction band edge lies above the TiO2 conduction band edge. For larger clusters the band alignment at the TiO2/PbS interface appears to be unfavorable for carrier transfer; these clusters do not contributeto photoconduction.

scholarly journals Carbon Self-Doped Carbon Nitride Nanosheets with Enhanced Visible-Light Photocatalytic Hydrogen Production

Catalysts ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 366 ◽  
Author(s):  
Hongwei Wang ◽  
Guiqing Huang ◽  
Zhiwei Chen ◽  
Weibing Li
Keyword(s):  
Hydrogen Production ◽  
Visible Light ◽  
Transfer Rate ◽  
Carbon Nitride ◽  
Photocatalytic Performance ◽  
Photocatalytic Hydrogen Production ◽  
Feasible Method ◽  
Carrier Transfer ◽  
Carbon Nitride Nanosheets ◽  
Visible Light Photocatalytic

In this study, we prepared carbon self-doped carbon nitride nanosheets through a glucose synergic co-condensation method. In the carbon self-doped structure, the N atoms in the triazine rings were substituted by C atoms, resulting in enhanced visible-light photocatalytic hydrogen production, which is three-times higher than that of bulk carbon nitride. The enhanced photocatalytic hydrogen production was attributed to the higher charge-carrier transfer rate and widened light absorption range of the carbon nitride nanosheets after carbon self-doping. Thus, this work highlights the importance of carbon self-doping for improving the photocatalytic performance. Meanwhile, it provides a feasible method for the preparation of carbon self-doped carbon nitride without destroying the 2D conjugated backbone structures.

Controlling Band Alignment at the Back Interface of Cadmium Telluride Solar Cells using ZnTe and Te Buffer Layers

MRS Advances ◽  
2019 ◽  
Vol 4 (16) ◽  
pp. 913-919 ◽  
Author(s):  
Fadhil K. Alfadhili ◽  
Adam B. Phillips ◽  
Geethika K. Liyanage ◽  
Jacob M. Gibbs ◽  
Manoj K. Jamarkattel ◽  
...  
Keyword(s):  
Solar Cells ◽  
Fill Factor ◽  
Critical Role ◽  
Open Circuit ◽  
Band Alignment ◽  
Buffer Layers ◽  
Device Performance ◽  
Band Bending ◽  
Cdte Solar Cells ◽  
Hole Current

ABSTRACTFormation of a low barrier back contact plays a critical role in improving the photoconversion efficiency of the CdTe solar cells. Incorporating a buffer layer to minimize the band bending at the back of the CdTe device can significantly lower the barrier for the hole current, improving open circuit voltage (VOC) and the fill factor. Over the past years, researchers have incorporated the both ZnTe and Te as buffer layers to improve CdTe device performance. Here we compare device performance using these two materials as buffer layers at the back of CdTe devices. We show that using Te in contact to CdTe results in higher performance than using ZnTe in contact to the CdTe. Low temperature current density-voltage measurements show that Te results is a lower barrier with CdTe than ZnTe, indicating that Te has better band alignment, resulting in less downward bending in the CdTe at the back interface, than ZnTe does.

Computational Mechanics Routes to Explore the Origin of Mechanical Properties in a Biological Nanocomposite: Nacre

2004 ◽  
Vol 844 ◽  
Author(s):  
Dinesh Katti ◽  
Kalpana Katti
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Computational Mechanics ◽  
Critical Role ◽  
Physical Restraint ◽  
Model System ◽  
Tensile Failure ◽  
Organic Layer ◽  
High Toughness ◽  
Free Relative

ABSTRACTNacre, the inner layer of seashells, is a laminated nanocomposite consisting of micron sized pseudo hexagonal aragonitic calcium carbonate platelets with about 20 nanometer thick organic layer sandwiched between the platelets. This nanocomposite has been studied extensively as a model system for the design of new biomimetic nanocomposites. The nano and micro architecture of nacre has many features and nuances, which have been attributed as possible reasons for the exceptional mechanical properties. In our work, we have used computational mechanics routes to model and simulate observed macro response, to quantitatively evaluate the contribution of various components of the nano and micro architecture of nacre to the mechanical properties. We also describe our discovery of platelet interlocks and their impact on the mechanical response of nacre. Our experiments on tensile failure and scanning electron microscopy of nacre specimens, and simulations using finite element modeling, indicate that the interlocks function as a physical restraint against free relative movement of platelets. Hence, these interlocking features need to yield/break before the complete transfer of load can occur to an intervening organic. The observed interlocks play a critical role in the mechanical response of nacre. During failure the features observed in the microstructure of nacre, such as relative rotation between platelet layers, platelet penetration, and other geometrical abnormalities such as an elongated side etc., appear not to be accidents of nature; they seem to exist for a purpose. These abnormalities lead to high toughness and strength, which is necessary for protecting the organism within the seashell.

Termination dependence and electric field modification of band alignment in a CNT/CH3NH3PbI3 heterojunction

2021 ◽  
Vol 23 (15) ◽  
pp. 9249-9258
Author(s):  
Qiuhong Tan ◽  
Qianjin Wang ◽  
Chao Zhang ◽  
Kunpeng Gao ◽  
Yuanfangzhou Wang ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Electric Field ◽  
Band Alignment ◽  
Carrier Transfer ◽  
Transfer Processes

The different charge carrier transfer processes as well as termination dependence of band alignment in the CNT/CH3NH3PbI3 heterojunction.

scholarly journals Enhanced charge separation in TiO2/nanocarbon hybrid photocatalysts through coupling with short carbon nanotubes

RSC Advances ◽  
2021 ◽  
Vol 11 (19) ◽  
pp. 11702-11713
Author(s):  
Ahmed Al Mayyahi ◽  
Brian M. Everhart ◽  
Tej B. Shrestha ◽  
Tyson C. Back ◽  
Placidus B. Amama
Keyword(s):  
Carbon Nanotubes ◽  
Electron Transfer ◽  
Hybrid Composite ◽  
Charge Separation ◽  
Critical Role ◽  
Graphitic Carbon ◽  
Photocatalytic Efficiency ◽  
Interfacial Contact ◽  
Transfer Behavior ◽  
Short Carbon

The interfacial contact between TiO2 and graphitic carbon in a hybrid composite plays a critical role in electron transfer behavior, and in turn, its photocatalytic efficiency.

scholarly journals Intermolecular Diastereoselective Annulation of Azaarenes into Fused N-heterocycles by Ru(II) Reductive Catalysis

2021 ◽  
Author(s):  
He Zhao ◽  
Yang Wu ◽  
Chenggang Ci ◽  
Zhenda Tan ◽  
Jian Yang ◽  
...  
Keyword(s):  
Building Block ◽  
Transfer Rate ◽  
Hydrogen Transfer ◽  
Functional Group ◽  
Critical Role ◽  
Hydride Transfer ◽  
Mechanistic Studies ◽  
Mild Conditions ◽  
Excellent Selectivity ◽  
Coupling Sequence

Abstract Despite the important advances in azaaryl C−H activation/functionalization, reductive functionalization of ubiquitously distributed but weakly reactive azaarenes remains to date a challenge. Herein, by a strategy incorporating a tandem coupling sequence into the reduction of azaarenes, we present a dearomative annulation of azaarenes into promising fused syn-N-heterocycles by combination with a large variety of aniline derivatives and paraformaldehyde under ruthenium(II) reductive catalysis, proceeding with excellent selectivity, mild conditions, and broad substrate and functional group compatibility. Mechanistic studies reveal that the products are formed via hydride transfer-initiated β-aminomethylation and α-arylation of the pyridyl core in azaarenes, paraformaldehyde serves as both the C1-building block and reductant precursor, and the use of Mg(OMe)2 base plays a critical role in determining the reaction chemo-selectivity by lowering the hydrogen transfer rate. The present work opens a door to further develop valuable reductive functionalization of unsaturated systems by taking profit of formaldehyde-endowed two functions.

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