scholarly journals Protecting hot carriers by tuning hybrid perovskite structures with alkali cations

2020 ◽  
Vol 6 (43) ◽  
pp. eabb1336 ◽  
Author(s):  
Ti Wang ◽  
Linrui Jin ◽  
Juanita Hidalgo ◽  
Weibin Chu ◽  
Jordan M. Snaider ◽  
...  
Keyword(s):  
Carrier Transport ◽  
Successful Implementation ◽  
Hot Carriers ◽  
Alkali Cations ◽  
Hot Carrier ◽  
Hybrid Perovskite ◽  
Carrier Temperature ◽  
High Carrier ◽  
Halide Perovskites ◽  
Effective Carrier

Successful implementation of hot carrier solar cells requires preserving high carrier temperature as carriers migrate through the active layer. Here, we demonstrated that addition of alkali cations in hybrid organic-inorganic lead halide perovskites led to substantially elevated carrier temperature, reduced threshold for phonon bottleneck, and enhanced hot carrier transport. The synergetic effects from the Rb, Cs, and K cations result in ~900 K increase in the effective carrier temperature at a carrier density around 1018 cm−3 with an excitation 1.45 eV above the bandgap. In the doped thin films, the protected hot carriers migrate 100 s of nanometers longer than the undoped sample as imaged by ultrafast microscopy. We attributed these improvements to the relaxation of lattice strain and passivation of halide vacancies by alkali cations based on x-ray structural characterizations and first principles calculations.

Monte Carlo Simulation of Boundary Scattering Effects for Power MOSFET Performance

2003 ◽  
Author(s):  
A. Marathe ◽  
D. G. Walker
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Carrier Transport ◽  
Hot Carriers ◽  
Power Mosfets ◽  
Hot Carrier ◽  
Microelectronic Devices ◽  
Interface Scattering ◽  
Scattering Effects ◽  
Hot Carrier Effects

Miniaturization of microelectronic devices has lead to many new issues not seen in larger structures, such as hot carrier effects and interfacial effects. In power MOSFETs, degradation of the transconductance can occur over the lifetime of a device. This decrease in performance is a result of hot carriers in the channel region scattering at a Si/SiO2 interface that has been passivated with hydrogen. Eventually hot carriers liberate the hydrogen, leaving silicon bonds with an entirely different scattering cross section. The current work presents a Monte Carlo simulation of carrier transport in silicon near an interface. Scattering parameters at the interface are parameterized and studied. It was found that electron mobility, which is proportional to transconductance, is a function of the energy loss rate and type of scattering at the interface. Results indicate that dangling bonds and H-Si bonds can be characterized by different scattering mechanisms.

USING OPTICALLY DETECTED CYCLOTRON RESONANCE TO STUDY ELECTRON-EXCITON AND ELECTRON-PHONON INTERACTIONS IN SEMICONDUCTORS

1993 ◽  
Vol 07 (08) ◽  
pp. 501-523
Author(s):  
TATSUYA TOMARU ◽  
TYUZI OHYAMA ◽  
EIZO OTSUKA
Keyword(s):  
Relaxation Process ◽  
Cyclotron Resonance ◽  
Carrier State ◽  
Polar Optical Phonon ◽  
Carrier Distribution ◽  
Electron Hole ◽  
Hot Carrier ◽  
Carrier Temperature ◽  
Optically Detected ◽  
Effective Carrier

We review our optically detected cyclotron resonance (ODCR) studies extending over Ge, Si and ZnSe. The following three subjects are taken up: (1) Impact dissociation of excitons by free carriers, which is dominated by electron-electron and hole-hole interactions rather than by electron-hole interaction. (2) The hot-carrier state produced in Ge and Si by cyclotron resonance is discussed in terms of hot-carrier-distribution function, effective carrier temperature, and carrier kinetics. (3) The relaxation process of photoexcited carriers in ZnSe is discussed. This relaxation process is found to be dominated by electron-polar-optical-phonon interaction, which gives rise to the polaron effect and to resonant formation of free excitons following one-LO-phonon emission. Thermally detected cyclotron resonance (TDCR) is also introduced.

scholarly journals Optimizing the quasi-equilibrium state of hot carriers in all-inorganic lead halide perovskite nanocrystals through Mn doping: fundamental dynamics and device perspectives

2022 ◽  
Author(s):  
Jie Meng ◽  
Zhenyun Lan ◽  
Weihua Lin ◽  
Mingli Liang ◽  
Xianshao Zou ◽  
...  
Keyword(s):  
Energy Loss ◽  
Equilibrium State ◽  
Quasi Equilibrium ◽  
Relaxation Dynamics ◽  
Hot Carriers ◽  
Hot Carrier ◽  
Halide Perovskites ◽  
Halide Perovskite ◽  
Mn Doped ◽  
Lead Halide

Hot carrier (HC) cooling accounts for the significant energy loss in lead halide perovskites (LHPs) solar cells. Here, we study HC relaxation dynamics in Mn-doped LHP CsPbI3 nanocrystals (NCs), combining...

Limits of Charge Carrier Transport in Halide Perovskites Revealed by Optical-Pump Terahertz-Probe Spectroscopy

2019 ◽  
Author(s):  
Hannes Hempel ◽  
Andrei Petsiu ◽  
Martin Stolterfoht ◽  
Pascal Becker ◽  
Dieter Neher ◽  
...  
Keyword(s):  
Charge Carrier ◽  
Carrier Transport ◽  
Charge Carrier Transport ◽  
Optical Pump ◽  
Halide Perovskites ◽  
Probe Spectroscopy

scholarly journals Hot-carriers in organic photovoltaics

2021 ◽  
Vol 93 (2) ◽  
pp. 223-230
Author(s):  
Palas Roy
Keyword(s):  
Organic Photovoltaics ◽  
Excess Energy ◽  
Charge Carriers ◽  
Hot Carriers ◽  
Hot Carrier ◽  
Improve Efficiency ◽  
Coulombic Attraction ◽  
Carrier Escape

Abstract Photogenerated charge carriers in organic photovoltaics (OPVs) suffer relaxation and recombination losses. However, extracting these carriers at higher energy (‘Hot-carriers’) has been found to be effective to overcome such loss pathways and improve efficiency of OPVs. Excess energy and long delocalization length promotes hot-carrier escape from Coulombic attraction and dissociation into free charges. Here, I have reviewed the ways to generate hot-carriers and their extraction in organic backbones. In-depth understanding of their energetics and dynamics will help designing hot-carrier photovoltaics.

Coupled-Langevin-equation analysis of hot-carrier transport in semiconductors

1992 ◽  
Vol 45 (4) ◽  
pp. 1903-1906 ◽  
Author(s):  
Tilmann Kuhn ◽  
Lino Reggiani ◽  
Luca Varani
Keyword(s):  
Langevin Equation ◽  
Carrier Transport ◽  
Hot Carrier ◽  
Equation Analysis

Improved Mobility and Bias Stability of Thin Film Transistors Using the Double-Layer a-InGaZnO/a-InGaZnO:N Channel

2016 ◽  
Vol 16 (4) ◽  
pp. 3659-3663
Author(s):  
H Yu ◽  
L Zhang ◽  
X. H Li ◽  
H. Y Xu ◽  
Y. C Liu
Keyword(s):  
Thin Film ◽  
Double Layer ◽  
Thin Film Transistors ◽  
Carrier Transport ◽  
Single Layer ◽  
Channel Structure ◽  
Gate Insulator ◽  
Large Area ◽  
Threshold Voltage Shift ◽  
High Carrier

The amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFTs) were demonstrated based on a double-layer channel structure, where the channel is composed of an ultrathin nitrogenated a-IGZO (a-IGZO:N) layer and an undoped a-IGZO layer. The double-layer channel device showed higher saturation mobility and lower threshold-voltage shift (5.74 cm2/Vs, 2.6 V) compared to its single-layer counterpart (0.17 cm2/Vs, 7.23 V). The improvement can be attributed to three aspects: (1) improved carrier transport properties of the channel by the a-IGZO:N layer with high carrier mobility and the a-IGZO layer with high carrier concentration, (2) reduced interfacial trap density between the active channel and the gate insulator, and (3) higher surface flatness of the double-layer channel. Our study reveals key insights into double-layer channel, involving selecting more suitable electrical property for back-channel layer and more suitable interface modification for active layer. Meanwhile, room temperature fabrication amorphous TFTs offer certain advantages on better flexibility and higher uniformity over a large area.

Determining plasmonic hot-carrier energy distributions via single-molecule transport measurements

Science ◽  
2020 ◽  
pp. eabb3457 ◽  
Author(s):  
Harsha Reddy ◽  
Kun Wang ◽  
Zhaxylyk Kudyshev ◽  
Linxiao Zhu ◽  
Shen Yan ◽  
...  
Keyword(s):  
Single Molecule ◽  
Plasmonic Nanostructures ◽  
Hot Carriers ◽  
Energy Distributions ◽  
Nanoscale Systems ◽  
Hot Carrier ◽  
Transport Measurements ◽  
Single Molecule Junctions ◽  
Molecule Transport ◽  
Carrier Energy

Hot-carriers in plasmonic nanostructures, generated via plasmon decay, play key roles in applications like photocatalysis and in photodetectors that circumvent band-gap limitations. However, direct experimental quantification of steady-state energy distributions of hot-carriers in nanostructures has so far been lacking. We present transport measurements from single-molecule junctions, created by trapping suitably chosen single molecules between an ultra-thin gold film supporting surface plasmon polaritons and a scanning probe tip, that can provide quantification of plasmonic hot-carrier distributions. Our results show that Landau damping is the dominant physical mechanism of hot-carrier generation in nanoscale systems with strong confinement. The technique developed in this work will enable quantification of plasmonic hot-carrier distributions in nanophotonic and plasmonic devices.

Thermally activated current–voltage asymmetry in quantum-well inter-subband photodetectors

1996 ◽  
Vol 74 (S1) ◽  
pp. 9-15 ◽  
Author(s):  
P. V. Kolev ◽  
M. J. Deen ◽  
H. C. Liu ◽  
Jianmeng Li ◽  
M. Buchanan ◽  
...  
Keyword(s):  
Quantum Well ◽  
Carrier Transport ◽  
Transport Phenomena ◽  
Infrared Region ◽  
Avalanche Photodetectors ◽  
Long Wavelength ◽  
Hot Carrier ◽  
Thermally Activated ◽  
Current Voltage ◽  
Long Wavelength Infrared

Continuing research interest in quantum-well inter-subband-based devices can be associated with its prospects for numerous optoelectronic applications in the long wavelength infrared region. This paper presents experimentally measured field dependence of the thermally activated effective-barrier lowering in quantum-well inter-subband photodetectors (QWIPs). This barrier lowering is considered to be the main cause of the commonly observed asymmetry in the current–voltage characteristics of QWIPs. The research results presented here are important for understanding the factors determining the dark-current mechanisms that are crucial for further improvement in the characteristics of these devices. The study of current-carrier transport phenomena in a quantum well is also of interest for developing quantum-well lasers and avalanche photodetectors based on intraband processes, and also transistors based on ballistic or hot carrier transport phenomena.

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