scholarly journals Long-lived charge separation following pump-wavelength–dependent ultrafast charge transfer in graphene/WS2 heterostructures

2021 ◽  
Vol 7 (9) ◽  
pp. eabd9061
Author(s):  
Shuai Fu ◽  
Indy du Fossé ◽  
Xiaoyu Jia ◽  
Jingyin Xu ◽  
Xiaoqing Yu ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Charge Separation ◽  
Transient Absorption ◽  
Transition Metal Dichalcogenides ◽  
Thermionic Emission ◽  
Great Promise ◽  
Metal Dichalcogenides ◽  
Ultrafast Charge Transfer ◽  
Device Operation ◽  
Interfacial Charge

Van der Waals heterostructures consisting of graphene and transition metal dichalcogenides have shown great promise for optoelectronic applications. However, an in-depth understanding of the critical processes for device operation, namely, interfacial charge transfer (CT) and recombination, has so far remained elusive. Here, we investigate these processes in graphene-WS2 heterostructures by complementarily probing the ultrafast terahertz photoconductivity in graphene and the transient absorption dynamics in WS2 following photoexcitation. We observe that separated charges in the heterostructure following CT live extremely long: beyond 1 ns, in contrast to ~1 ps charge separation reported in previous studies. This leads to efficient photogating of graphene. Furthermore, for the CT process across graphene-WS2 interfaces, we find that it occurs via photo-thermionic emission for sub-A-exciton excitations and direct hole transfer from WS2 to the valence band of graphene for above-A-exciton excitations. These findings provide insights to further optimize the performance of optoelectronic devices, in particular photodetection.

THE ELECTRONIC STRUCTURE AT ORGANIC–2D MATERIAL HETEROINTERFACES

2021 ◽  
pp. 2140003
Author(s):  
YU LI HUANG ◽  
ANDREW THYE SHEN WEE
Keyword(s):  
Charge Transfer ◽  
Electronic Structures ◽  
Transition Metal Dichalcogenides ◽  
2D Material ◽  
Physical Mechanisms ◽  
Wide Range ◽  
Fundamental Understanding ◽  
Potential Applications ◽  
Metal Dichalcogenides ◽  
Interfacial Charge

Organic–2D material heterostructures have attracted intensive research interest due to their intriguing properties, with a wide range of potential applications in multifunctional flexible electronic and optoelectronic devices. Central to the realization of such devices is a fundamental understanding of the electronic structures at organic–2D material heterointerfaces. The energy level alignment (ELA) at the interface is of paramount importance because it determines the charge transfer barriers between the two materials in contact. In this paper, we discuss the physical mechanisms determining the ELAs, with special attention on interfacial charge transfer at the heterostructures. We review the current understanding of electronic properties at the heterointerfaces formed by the integration of organics with graphene and 2D transition metal dichalcogenides (TMDs), and conclude with a perspective on the future development of organic–2D material heterostructure.

Photoinitiated multi-step charge separation and ultrafast charge transfer induced dissociation in a pyridyl-linked photosensitizer–cobaloxime assembly

2013 ◽  
Vol 6 (6) ◽  
pp. 1917 ◽  
Author(s):  
Brad S. Veldkamp ◽  
Won-Sik Han ◽  
Scott M. Dyar ◽  
Samuel W. Eaton ◽  
Mark A. Ratner ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Charge Separation ◽  
Ultrafast Charge Transfer

Strong-coupled hybrid structure of carbon nanotube and MoS2 monolayer with ultrafast interfacial charge transfer

Nanoscale ◽  
2019 ◽  
Vol 11 (37) ◽  
pp. 17195-17200 ◽  
Author(s):  
Can Liu ◽  
Hao Hong ◽  
Qinghe Wang ◽  
Ping Liu ◽  
Yonggang Zuo ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Carbon Nanotube ◽  
Strong Coupling ◽  
Hybrid Structure ◽  
Interfacial Charge Transfer ◽  
Mos2 Monolayer ◽  
Ultrafast Charge Transfer ◽  
Interfacial Charge

A strong-coupled nanotube-MoS2 hybrid structure is constructed, which shows strong coupling and ultrafast charge transfer across the interface.

scholarly journals Additive manufacturing of patterned 2D semiconductor through recyclable masked growth

2019 ◽  
Vol 116 (9) ◽  
pp. 3437-3442 ◽  
Author(s):  
Yunfan Guo ◽  
Pin-Chun Shen ◽  
Cong Su ◽  
Ang-Yu Lu ◽  
Marek Hempel ◽  
...  
Keyword(s):  
Electronic Materials ◽  
Field Effect Transistors ◽  
2D Materials ◽  
Direct Synthesis ◽  
Scale Up ◽  
Transition Metal Dichalcogenides ◽  
Chemical Vapor ◽  
Great Promise ◽  
Substrate Engineering ◽  
Metal Dichalcogenides

The 2D van der Waals crystals have shown great promise as potential future electronic materials due to their atomically thin and smooth nature, highly tailorable electronic structure, and mass production compatibility through chemical synthesis. Electronic devices, such as field effect transistors (FETs), from these materials require patterning and fabrication into desired structures. Specifically, the scale up and future development of “2D”-based electronics will inevitably require large numbers of fabrication steps in the patterning of 2D semiconductors, such as transition metal dichalcogenides (TMDs). This is currently carried out via multiple steps of lithography, etching, and transfer. As 2D devices become more complex (e.g., numerous 2D materials, more layers, specific shapes, etc.), the patterning steps can become economically costly and time consuming. Here, we developed a method to directly synthesize a 2D semiconductor, monolayer molybdenum disulfide (MoS2), in arbitrary patterns on insulating SiO2/Si via seed-promoted chemical vapor deposition (CVD) and substrate engineering. This method shows the potential of using the prepatterned substrates as a master template for the repeated growth of monolayer MoS2 patterns. Our technique currently produces arbitrary monolayer MoS2 patterns at a spatial resolution of 2 μm with excellent homogeneity and transistor performance (room temperature electron mobility of 30 cm2 V−1 s−1 and on–off current ratio of 107). Extending this patterning method to other 2D materials can provide a facile method for the repeatable direct synthesis of 2D materials for future electronics and optoelectronics.

scholarly journals Long-lived and disorder-free charge transfer states enable endothermic charge separation in efficient non-fullerene organic solar cells

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ture F. Hinrichsen ◽  
Christopher C. S. Chan ◽  
Chao Ma ◽  
David Paleček ◽  
Alexander Gillett ◽  
...  
Keyword(s):  
Solar Cells ◽  
Charge Transfer ◽  
Organic Solar Cells ◽  
Charge Separation ◽  
Free Charge ◽  
Charge Generation ◽  
Time Resolved ◽  
Thermodynamic Conditions ◽  
Donor Acceptor ◽  
Interfacial Charge

Abstract Organic solar cells based on non-fullerene acceptors can show high charge generation yields despite near-zero donor–acceptor energy offsets to drive charge separation and overcome the mutual Coulomb attraction between electron and hole. Here, we use time-resolved optical spectroscopy to show that free charges in these systems are generated by thermally activated dissociation of interfacial charge-transfer states that occurs over hundreds of picoseconds at room temperature, three orders of magnitude slower than comparable fullerene-based systems. Upon free electron–hole encounters at later times, both charge-transfer states and emissive excitons are regenerated, thus setting up an equilibrium between excitons, charge-transfer states and free charges. Our results suggest that the formation of long-lived and disorder-free charge-transfer states in these systems enables them to operate closely to quasi-thermodynamic conditions with no requirement for energy offsets to drive interfacial charge separation and achieve suppressed non-radiative recombination.

Highly-efficient heterojunction solar cells based on two-dimensional tellurene and transition metal dichalcogenides

2019 ◽  
Vol 7 (13) ◽  
pp. 7430-7436 ◽  
Author(s):  
Kai Wu ◽  
Huanhuan Ma ◽  
Yunzhi Gao ◽  
Wei Hu ◽  
Jinlong Yang
Keyword(s):  
Solar Cells ◽  
Transition Metal ◽  
Charge Separation ◽  
Transition Metal Dichalcogenides ◽  
Band Alignment ◽  
Type Ii ◽  
Two Dimensional ◽  
Heterojunction Solar Cells ◽  
Highly Efficient ◽  
Metal Dichalcogenides

Tellurene and TMDs show desirable type II band alignment for constructing highly-efficient heterojunction solar cells with strong charge separation and enhanced sunlight absorption.

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