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

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

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

Small ◽

10.1002/smll.201702163 ◽

2017 ◽

Vol 13 (41) ◽

pp. 1702163 ◽

Cited By ~ 23

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

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

Frontiers in Physics ◽

10.3389/fphy.2021.668149 ◽

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.

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

Physical Review Letters ◽

10.1103/physrevlett.79.269 ◽

1997 ◽

Vol 79 (2) ◽

pp. 269-272 ◽

Cited By ~ 107

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

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

Scientific Reports ◽

10.1038/s41598-020-73152-7 ◽

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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