scholarly journals Highly efficient hot electron harvesting from graphene before electron-hole thermalization

2019 ◽  
Vol 5 (11) ◽  
pp. eaax9958 ◽  
Author(s):  
Yuzhong Chen ◽  
Yujie Li ◽  
Yida Zhao ◽  
Hongzhi Zhou ◽  
Haiming Zhu
Keyword(s):  
Solar Cell ◽  
Quantum Yield ◽  
Nonlinear Behavior ◽  
Hot Electrons ◽  
Hot Electron ◽  
New Paradigm ◽  
Electron Hole ◽  
Mid Infrared ◽  
Hot Carrier ◽  
Carrier Thermalization

Although the unique hot carrier characteristics in graphene suggest a new paradigm for hot carrier–based energy harvesting, the reported efficiencies with conventional photothermoelectric and photothermionic emission pathways are quite low because of inevitable hot carrier thermalization and cooling loss. Here, we proposed and demonstrated the possibility of efficiently extracting hot electrons from graphene after carrier intraband scattering but before electron-hole interband thermalization, a new regime that has never been reached before. Using various layered semiconductors as model electron-accepting components, we generally observe ultrafast injection of energetic hot electrons from graphene over a very broad photon energy range (visible to mid-infrared). The injection quantum yield reaches as high as ~50%, depending on excitation energy but remarkably, not on fluence, in notable contrast with conventional pathways with nonlinear behavior. Hot electron harvesting in this regime prevails over energy and carrier loss and closely resembles the concept of hot carrier solar cell.

scholarly journals Macroscopic Assembled Graphene for Silicon Mid-Infrared Photodetectors

2020 ◽  
Author(s):  
Chao Gao ◽  
Li Peng ◽  
Sichao Du ◽  
Lixiang Liu ◽  
Srikrishna Bodepudi ◽  
...  
Keyword(s):  
Impact Ionization ◽  
Single Layer ◽  
Atomic Scale ◽  
Hot Electrons ◽  
Single Layer Graphene ◽  
Quantum Yields ◽  
Infrared Range ◽  
Mid Infrared ◽  
Hot Carrier ◽  
Layer Graphene

Abstract Graphene with linear energy dispersion and weak electron-phonon interaction is highly anticipated to harvest hot-electrons in a broad wavelength range from ultraviolet to terahertz. However, the limited absorption (~2.3%) and serious backscattering of hot-electrons associated with single-layer graphene result in inadequate quantum yields, impeding their practically broadband photodetection, especially in the mid-infrared range. Here, we report a macroscopic assembled graphene (MAG)/silicon heterojunction for ultrafast mid-infrared photodetection. The highly crystalline 2-inch scale MAG with tunable thickness from 10 to 60 nm is produced by scalable wet-assembly of commercial graphene oxide followed by thermal annealing. The MAG/Si Schottky diode exhibits broadband photodetection capability in 1-10 μm at room temperature with fast response (120-130 ns, 4 mm2 window) and high detectivity (1011 to 106 Jones), outperforming single-layer graphene/Si photodetectors by 2 to 8 orders in transient photocurrent. This optoelectronic performance is attributed to the superior advantages of MAG (~40% of light absorption, ~23 ps of carrier relaxation time, and high quasi-equilibrated hot-carrier-multiplication gain), atomic-scale contact interface of MAG and silicon, and impact-ionization avalanche gain (~100 times) from silicon. The MAG provides a long-range platform to understand the hot-carrier dynamics in stacked 2D materials, leading to next-generation broadband silicon-based image sensors.

Quantification of hot carrier thermalization in PbS colloidal quantum dots by power and temperature dependent photoluminescence spectroscopy

RSC Advances ◽  
2016 ◽  
Vol 6 (93) ◽  
pp. 90846-90855 ◽  
Author(s):  
Wenkai Cao ◽  
Zewen Zhang ◽  
Rob Patterson ◽  
Yuan Lin ◽  
Xiaoming Wen ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Solar Cell ◽  
Photoluminescence Spectroscopy ◽  
Colloidal Quantum Dots ◽  
Temperature Dependent ◽  
Hot Carrier ◽  
Carrier Thermalization ◽  
Temperature Dependent Photoluminescence

PbS QDs are studied as attractive candidates to be applied as hot carrier solar cell absorbers.

scholarly journals Ab initio study of hot electrons in GaAs

2015 ◽  
Vol 112 (17) ◽  
pp. 5291-5296 ◽  
Author(s):  
Marco Bernardi ◽  
Derek Vigil-Fowler ◽  
Chin Shen Ong ◽  
Jeffrey B. Neaton ◽  
Steven G. Louie
Keyword(s):  
Ab Initio ◽  
Phonon Scattering ◽  
Carrier Dynamics ◽  
Hot Electrons ◽  
Hot Electron ◽  
Hot Carriers ◽  
Hot Carrier ◽  
Acoustic Modes ◽  
Decay Times ◽  
Electron Phonon Scattering

Hot carrier dynamics critically impacts the performance of electronic, optoelectronic, photovoltaic, and plasmonic devices. Hot carriers lose energy over nanometer lengths and picosecond timescales and thus are challenging to study experimentally, whereas calculations of hot carrier dynamics are cumbersome and dominated by empirical approaches. In this work, we present ab initio calculations of hot electrons in gallium arsenide (GaAs) using density functional theory and many-body perturbation theory. Our computed electron–phonon relaxation times at the onset of the Γ, L, and X valleys are in excellent agreement with ultrafast optical experiments and show that the ultrafast (tens of femtoseconds) hot electron decay times observed experimentally arise from electron–phonon scattering. This result is an important advance to resolve a controversy on hot electron cooling in GaAs. We further find that, contrary to common notions, all optical and acoustic modes contribute substantially to electron–phonon scattering, with a dominant contribution from transverse acoustic modes. This work provides definitive microscopic insight into hot electrons in GaAs and enables accurate ab initio computation of hot carriers in advanced materials.

scholarly journals Reversible electron–hole separation in a hot carrier solar cell

2015 ◽  
Vol 17 (9) ◽  
pp. 095004 ◽  
Author(s):  
S Limpert ◽  
S Bremner ◽  
H Linke
Keyword(s):  
Solar Cell ◽  
Electron Hole ◽  
Hot Carrier

Electron–hole drops in -stressed germanium

1985 ◽  
Vol 63 (3) ◽  
pp. 387-392
Author(s):  
T. Timusk ◽  
R. W. Scholes ◽  
H. G. Zarate
Keyword(s):  
Phase Separation ◽  
High Frequency ◽  
Mie Theory ◽  
Low Frequency ◽  
Hot Electrons ◽  
Low Density ◽  
Hot Electron ◽  
Small Drop ◽  
Electron Component ◽  
Electron Hole

We show, using the Mie theory, that the phase separation of electron–hole drops in [Formula: see text]-stressed Ge, predicted by Kirzcenow and Singwi, can be observed by the splitting of the plasma resonance into two components, a high frequency line arising from the dense, hot-electron component and a low frequency line from the low density shell. We also present extinction measurements on electron–hole drops that show that in samples with small drop radii the phase separation does indeed take place as predicted. Samples that contain large drops show the presence of hot electrons but the phase separation is difficult to observe by our technique.

scholarly journals Plasmonic hot-electron photodetection with quasi-bound states in the continuum and guided resonances

Nanophotonics ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Wenhao Wang ◽  
Lucas V. Besteiro ◽  
Peng Yu ◽  
Feng Lin ◽  
Alexander O. Govorov ◽  
...  
Keyword(s):  
Bound States ◽  
Structural Parameters ◽  
Hybrid Structure ◽  
Fine Tuning ◽  
Hot Electrons ◽  
Hot Electron ◽  
Perfect Absorption ◽  
High Loss ◽  
Guided Mode ◽  
The Continuum

Abstract Hot electrons generated in metallic nanostructures have shown promising perspectives for photodetection. This has prompted efforts to enhance the absorption of photons by metals. However, most strategies require fine-tuning of the geometric parameters to achieve perfect absorption, accompanied by the demanding fabrications. Here, we theoretically propose a Ag grating/TiO2 cladding hybrid structure for hot electron photodetection (HEPD) by combining quasi-bound states in the continuum (BIC) and plasmonic hot electrons. Enabled by quasi-BIC, perfect absorption can be readily achieved and it is robust against the change of several structural parameters due to the topological nature of BIC. Also, we show that the guided mode can be folded into the light cone by introducing a disturbance to become a guided resonance, which then gives rise to a narrow-band HEPD that is difficult to be achieved in the high loss gold plasmonics. Combining the quasi-BIC and the guided resonance, we also realize a multiband HEPD with near-perfect absorption. Our work suggests new routes to enhance the light-harvesting in plasmonic nanosystems.

scholarly journals Superior photo-carrier diffusion dynamics in organic-inorganic hybrid perovskites revealed by spatiotemporal conductivity imaging

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xuejian Ma ◽  
Fei Zhang ◽  
Zhaodong Chu ◽  
Ji Hao ◽  
Xihan Chen ◽  
...  
Keyword(s):  
Thin Films ◽  
Solar Cell ◽  
Relaxation Times ◽  
Charge Trapping ◽  
Free Carrier ◽  
Carrier Dynamics ◽  
Electron Hole ◽  
Inorganic Hybrid ◽  
Diffusion Dynamics ◽  
The Difference

AbstractThe outstanding performance of organic-inorganic metal trihalide solar cells benefits from the exceptional photo-physical properties of both electrons and holes in the material. Here, we directly probe the free-carrier dynamics in Cs-doped FAPbI3 thin films by spatiotemporal photoconductivity imaging. Using charge transport layers to selectively quench one type of carriers, we show that the two relaxation times on the order of 1 μs and 10 μs correspond to the lifetimes of electrons and holes in FACsPbI3, respectively. Strikingly, the diffusion mapping indicates that the difference in electron/hole lifetimes is largely compensated by their disparate mobility. Consequently, the long diffusion lengths (3~5 μm) of both carriers are comparable to each other, a feature closely related to the unique charge trapping and de-trapping processes in hybrid trihalide perovskites. Our results unveil the origin of superior diffusion dynamics in this material, crucially important for solar-cell applications.

Valley Photovoltaics and the Search for the Hot Carrier Solar Cell

2020 ◽  
Author(s):  
David K. Ferry ◽  
Stephen M. Goodnick ◽  
Ian R. Sellers ◽  
Vincent R. Whiteside
Keyword(s):  
Solar Cell ◽  
Hot Carrier
Sign in / Sign up

Export Citation Format

Share Document