Understanding the Electronic Structure of Graphene Quantum Dot-Fullerene Nanohybrids for Photovoltaic Applications

2016 ◽  
Vol 230 (5-7) ◽  
Author(s):  
Chandrima Chakravarty ◽  
Poulami Ghosh ◽  
Bikash Mandal ◽  
Pranab Sarkar
Keyword(s):  
Electronic Structure ◽  
Quantum Dot ◽  
Hybrid Systems ◽  
Density Functional ◽  
Band Alignment ◽  
Type I ◽  
Type Ii ◽  
Graphene Quantum Dot ◽  
Band Energy ◽  
Form Type

AbstractBy using density-functional tight-binding method we have calculated the electronic structure of graphene quantum dot (GQD)-fullerene hybrid systems and explored the efficacy of their use in designing solar cells. We have shown that the electronic energy levels of the nanohybrids can be tuned either by varying the size of the quantum dots or by proper functionalization of the quantum dot (QD). The GQD-fullerene nanohybrids form type-I or type-II band energy alignment depending upon the size of the GQD. Thus, hybrid systems with smaller sized QDs form type-II band energy alignment while those of larger GQDs form type-I alignment. The type-II band alignment confirms the spatial charge separation for the systems and thus the rate of recombination of charge carriers will be low. The value of

Type I–type II band alignment of a GaAsSb/InAs/GaAs quantum dot heterostructure influenced by dot size and strain-reducing layer composition

2013 ◽  
Vol 46 (9) ◽  
pp. 095103 ◽  
Author(s):  
A Hospodková ◽  
M Zíková ◽  
J Pangrác ◽  
J Oswald ◽  
J Kubištová ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Band Alignment ◽  
Type I ◽  
Type Ii ◽  
Gaas Quantum Dot ◽  
Layer Composition

The influence of Sb content and dots size of InAs/GaAs(1-x)Sbx quantum dot on type I-type II band alignment and carrier dynamics

2017 ◽  
Vol 122 (22) ◽  
pp. 225701
Author(s):  
Yaqian Li ◽  
Lian Ji ◽  
Shulong Lu ◽  
Chao Ding ◽  
Jianqiu Zhou
Keyword(s):  
Quantum Dot ◽  
Carrier Dynamics ◽  
Band Alignment ◽  
Type I ◽  
Type Ii

SPACE-CHARGE SPECTROSCOPY OF ELECTRONIC STATES IN Ge/Si QUANTUM DOTS WITH TYPE-II BAND ALIGNMENT

2007 ◽  
Vol 06 (05) ◽  
pp. 353-356
Author(s):  
A. I. YAKIMOV ◽  
A. V. DVURECHENSKII ◽  
A. I. NIKIFOROV ◽  
A. A. BLOSHKIN
Keyword(s):  
Quantum Dots ◽  
Electronic Structure ◽  
Binding Energy ◽  
Space Charge ◽  
Tensile Strain ◽  
Electronic States ◽  
Band Alignment ◽  
Type Ii ◽  
Electron Confinement ◽  
Si Quantum Dots

Space-charge spectroscopy was employed to study electronic structure in a stack of four layers of Ge quantum dots coherently embedded in an n-type Si (001) matrix. Evidence for an electron confinement in the vicinity of Ge dots was found. From the frequency-dependent measurements the electron binding energy was determined to be ~50 meV, which is consistent with the results of numerical analysis. The data are explained by a modification of the conduction band alignment induced by inhomogeneous tensile strain in Si around the buried Ge dots.

Interfacial defect engineering and Photocatalysis Properties of hBN/MX2(M = Mo, W, and X = S, Se) Heterostructures

2021 ◽  
Author(s):  
Zhihai Sun ◽  
Jiaxi Liu ◽  
Ying Zhang ◽  
Ziyuan Li ◽  
Leyu Peng ◽  
...  
Keyword(s):  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Band Alignment ◽  
Type I ◽  
Defect Engineering ◽  
Wide Range ◽  
Interfacial Defects ◽  
Significant Research ◽  
P Type ◽  
The Impact

Abstract Van der Waals (VDW) heterostructures have attracted significant research interest due to their tunable interfacial properties and potential in a wide range of applications such as electronics, optoelectronic, and heterocatalysis. In this work, the impact of interfacial defects on the electronic structures and photocatalytic properties of hBN/MX2(M = Mo, W, and X = S, Se) are studied using density functional theory calculations. The results reveal that the band alignment of hBN/MX2 can be adjusted by introducing vacancies and atomic doping. The type-I band alignment of the host structure was maintained in the heterostructure with n-type doping in the hBN sublayer. Interestingly, the band alignment changed to the type-II heterostructrue as VB defect and p-type doping was introduced in the hBN sublayer. This could be profitable for the separation of photo-generated electron−hole pairs at the interfaces and is highly desired for heterostructure photocatalysis. In addition, two Z-type heterostructures including hBN(BeB)/MoS2, hBN(BeB)/MoSe2, and hBN(VN)/MoSe2 were achieved, showing reducing band gap and ideal redox potential for water splitting. Our results reveal the possibility of engineering the interfacial and photocatalysis properties of hBN/MX2 heterostructures via interfacial defects.

scholarly journals Efficient Photocatalytic Hydrogen Evolution via Band Alignment Tailoring: Controllable Transition from Type-I to Type-II

Small ◽  
2017 ◽  
Vol 13 (41) ◽  
pp. 1702163 ◽  
Author(s):  
Zhongzhou Cheng ◽  
Fengmei Wang ◽  
Tofik Ahmed Shifa ◽  
Chao Jiang ◽  
Quanlin Liu ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Band Alignment ◽  
Type I ◽  
Type Ii ◽  
Photocatalytic Hydrogen Evolution

Electronic structure of GaAs/AlAs symmetric superlattices: A high-pressure study near the type-I–type-II crossover

1990 ◽  
Vol 41 (6) ◽  
pp. 3641-3646 ◽  
Author(s):  
M. Holtz ◽  
R. Cingolani ◽  
K. Reimann ◽  
R. Muralidharan ◽  
K. Syassen ◽  
...  
Keyword(s):  
High Pressure ◽  
Electronic Structure ◽  
Type I ◽  
Type Ii ◽  
High Pressure Study

scholarly journals Ultrafast Charge Separation in Bilayer WS2/Graphene Heterostructure Revealed by Time- and Angle-Resolved Photoemission Spectroscopy

2021 ◽  
Vol 9 ◽  
Author(s):  
Razvan Krause ◽  
Mariana Chávez-Cervantes ◽  
Sven Aeschlimann ◽  
Stiven Forti ◽  
Filippo Fabbri ◽  
...  
Keyword(s):  
Charge Separation ◽  
Graphene Layer ◽  
Optoelectronic Devices ◽  
Visible Spectral Range ◽  
Band Alignment ◽  
Photoemission Spectroscopy ◽  
Type I ◽  
Type Ii ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Indirect Band Gap

Efficient light harvesting devices need to combine strong absorption in the visible spectral range with efficient ultrafast charge separation. These features commonly occur in novel ultimately thin van der Waals heterostructures with type II band alignment. Recently, ultrafast charge separation was also observed in monolayer WS2/graphene heterostructures with type I band alignment. Here we use time- and angle-resolved photoemission spectroscopy to show that ultrafast charge separation also occurs at the interface between bilayer WS2 and graphene indicating that the indirect band gap of bilayer WS2 does not affect the charge transfer to the graphene layer. The microscopic insights gained in the present study will turn out to be useful for the design of novel optoelectronic devices.

Type II Band Alignment inSi1−xGex/Si(001)Quantum Wells: The Ubiquitous Type I Luminescence Results from Band Bending

1997 ◽  
Vol 79 (2) ◽  
pp. 269-272 ◽  
Author(s):  
M. L. W. Thewalt ◽  
D. A. Harrison ◽  
C. F. Reinhart ◽  
J. A. Wolk ◽  
H. Lafontaine
Keyword(s):  
Quantum Wells ◽  
Band Alignment ◽  
Type I ◽  
Type Ii ◽  
Band Bending

Tunable type-II band alignment and electronic structure of C3N4/MoSi2N4 heterostructure: Interlayer coupling and electric field

2022 ◽  
Vol 105 (4) ◽  
Author(s):  
Cuong Q. Nguyen ◽  
Yee Sin Ang ◽  
Son-Tung Nguyen ◽  
Nguyen V. Hoang ◽  
Nguyen Manh Hung ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Electric Field ◽  
Interlayer Coupling ◽  
Band Alignment ◽  
Type Ii

scholarly journals PN/PAs-WSe2 van der Waals heterostructures for solar cell and photodetector

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Xinyi Zheng ◽  
Yadong Wei ◽  
Kaijuan Pang ◽  
Ngeywo Kaner Tolbert ◽  
Dalin Kong ◽  
...  
Keyword(s):  
Refractive Index ◽  
Solar Cells ◽  
Negative Refractive Index ◽  
Wide Spectrum ◽  
Van Der Waals ◽  
Band Alignment ◽  
Ultraviolet Region ◽  
Type I ◽  
Type Ii ◽  
Van Der Waals Heterostructures

Abstract By first-principles calculations, we investigate the geometric stability, electronic and optical properties of the type-II PN-WSe2 and type-I PAs-WSe2 van der Waals heterostructures(vdWH). They are p-type semiconductors with indirect band gaps of 1.09 eV and 1.08 eV based on PBE functional respectively. By applying the external gate field, the PAs-WSe2 heterostructure would transform to the type-II band alignment from the type-I. With the increasing of magnitude of the electric field, two heterostructures turn into the n-type semiconductors and eventually into metal. Especially, PN/PAs-WSe2 vdWH are both high refractive index materials at low frequencies and show negative refractive index at high frequencies. Because of the steady absorption in ultraviolet region, the PAs-WSe2 heterostructure is a highly sensitive UV detector material with wide spectrum. The type-II PN-WSe2 heterostructure possesses giant and broadband absorption in the near-infrared and visible regions, and its solar power conversion efficiency of 13.8% is higher than the reported GaTe–InSe (9.1%), MoS2/p-Si (5.23%) and organic solar cells (11.7%). It does project PN-WSe2 heterostructure a potential for application in excitons-based solar cells.

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