The impact of cation and anion pairing in ionic salts on surface defect passivation in cesium lead bromide nanocrystals

2021 ◽  
Author(s):  
Lucy U. Yoon ◽  
Matthew R. Alpert ◽  
Hongxi Luo ◽  
Michael I. Schapowal ◽  
Eric N. Holmgren ◽  
...  
Keyword(s):  
Surface Defect ◽  
Binding Strength ◽  
Charge Trap ◽  
Ionic Salts ◽  
Lead Bromide ◽  
Defect Passivation ◽  
The Impact

Binding strength between cation and anion in a ligand has a major impact on their charge trap passivation efficacy.

scholarly journals Machining force comparison for surface defect hard turning and conventional hard turning of AISI 52100 steel

2021 ◽  
Vol 13 (3) ◽  
pp. 205-214
Author(s):  
P. U MAMAHESWARRAO ◽  
D. RANGARAJU ◽  
K. N. S. SUMAN ◽  
B. RAVISANKAR
Keyword(s):  
Hard Turning ◽  
Surface Defect ◽  
Cutting Speed ◽  
Tool Geometry ◽  
Depth Of Cut ◽  
Nose Radius ◽  
Aisi 52100 ◽  
Machining Force ◽  
Aisi 52100 Steel ◽  
The Impact

In this article, a recently developed method called surface defect machining (SDM) for hard turning has been adopted and termed surface defect hard turning (SDHT). The main purpose of the present study was to explore the impact of cutting parameters like cutting speed, feed, depth of cut, and tool geometry parameters such as nose radius and negative rake angle of the machining force during surface defect hard turning (SDHT) of AISI 52100 steel in dry condition with Polycrystalline cubic boron nitride (PCBN) tool; and results were compared with conventional hard turning (CHT). Experimentation is devised and executed as per Central Composite Design (CCD) of Response Surface Methodology (RSM). Results reported that an average machining force was decreased by 22% for surface defect hard turning (SDHT) compared to conventional hard turning (CHT).

Deep UV Photodetectors fabricated from CVD Single Crystal Diamond

2009 ◽  
Vol 1203 ◽  
Author(s):  
Mose Bevilacqua ◽  
Richard B. Jackman
Keyword(s):  
Single Crystal ◽  
Surface Damage ◽  
High Quality ◽  
Uv Photodetectors ◽  
Single Crystal Diamond ◽  
Defect Passivation ◽  
Deep Uv ◽  
Passivation Treatment ◽  
Homoepitaxial Layers ◽  
The Impact

AbstractDeep UV detection using a single crystal diamond (SCD) substrate without a homoepitaxial layer has been demonstrated using a defect passivation treatment. Despite evidence of surface damage on the SCD, the treatments lead to highly effective photoconductive devices, displaying six-orders of discrimination between deep UV and visible light and a responsivity as high as 100A/W, equivalent to an external quantum efficiency of 700, similar to the best values for devices based on high quality homoepitaxial layers. Impedance spectroscopic investigations suggest that the treatment used reduces the impact of less resistive surface material, most likely defects left from substrate polishing.

A Charge Storage Based Enhancement Mode AlGaN/GaN High Electron Mobility Transistor

2018 ◽  
Vol 913 ◽  
pp. 870-875 ◽  
Author(s):  
Hui Wang ◽  
Ling Li Jiang ◽  
Ning Wang ◽  
Hong Yu Yu ◽  
Xin Peng Lin
Keyword(s):  
Electron Mobility ◽  
Gate Dielectric ◽  
High Electron Mobility Transistor ◽  
Charge Storage ◽  
High Electron ◽  
High Electron Mobility ◽  
Charge Trap ◽  
Enhancement Mode ◽  
A Charge ◽  
The Impact

In this work, a charge storage based enhancement mode (E-mode) AlGaN/GaN high electron mobility transistor (HEMT) is proposed and studied. A stacked gate dielectrics, consisting of a tunnel oxide, a charge trap layer and a blocking oxide are applied in the HEMT structure. The E-mode can be realized by negative charge storage within the charge trap layer during the programming process. The impact of the programming condition and the thickness of the dielectrics on the threshold voltage (Vth) are simulated systematically. It is found that the Vth increases with the increasing programming voltage and time due to the increase of the storage charge. Under proper programming condition, the Vth can be increased to more than 2 V. Moreover, It is also found that the Vth increases with the decrease of the thickness of the dielectrics. In addition, it is found that the breakdown voltage of such HEMT can be adjusted by varying the gate dielectric stacks.

scholarly journals Constructive molecular configurations for surface-defect passivation of perovskite photovoltaics

Science ◽  
2019 ◽  
Vol 366 (6472) ◽  
pp. 1509-1513 ◽  
Author(s):  
Rui Wang ◽  
Jingjing Xue ◽  
Kai-Li Wang ◽  
Zhao-Kui Wang ◽  
Yanqi Luo ◽  
...  
Keyword(s):  
Surface Defect ◽  
High Efficiency ◽  
Ionic Character ◽  
Molecular Defect ◽  
Molecular Configuration ◽  
Surface Trap ◽  
Hydrogen Bond Formation ◽  
Metal Halide Perovskite ◽  
Defect Passivation ◽  
Molecule Design

Surface trap–mediated nonradiative charge recombination is a major limit to achieving high-efficiency metal-halide perovskite photovoltaics. The ionic character of perovskite lattice has enabled molecular defect passivation approaches through interaction between functional groups and defects. However, a lack of in-depth understanding of how the molecular configuration influences the passivation effectiveness is a challenge to rational molecule design. Here, the chemical environment of a functional group that is activated for defect passivation was systematically investigated with theophylline, caffeine, and theobromine. When N-H and C=O were in an optimal configuration in the molecule, hydrogen-bond formation between N-H and I (iodine) assisted the primary C=O binding with the antisite Pb (lead) defect to maximize surface-defect binding. A stabilized power conversion efficiency of 22.6% of photovoltaic device was demonstrated with theophylline treatment.

Study on Surface-defect Passivation of InP System Quantum Dots by Photochemical Method

2017 ◽  
Vol 24 (6) ◽  
pp. 489-493 ◽  
Author(s):  
Doyeon Kim ◽  
Hyun-Su Park ◽  
Hye Mi Cho ◽  
Bum-Sung Kim ◽  
Woo-Byoung Kim
Keyword(s):  
Quantum Dots ◽  
Surface Defect ◽  
Photochemical Method ◽  
Defect Passivation ◽  
System Quantum

Surface Defect Passivation and Reaction of c-Si in H2S

Langmuir ◽  
2017 ◽  
Vol 33 (51) ◽  
pp. 14580-14585 ◽  
Author(s):  
Hsiang-Yu Liu ◽  
Ujjwal K. Das ◽  
Robert W. Birkmire
Keyword(s):  
Surface Defect ◽  
Defect Passivation

scholarly journals Core–shell ZnO:Ga-SiO2 nanocrystals: limiting particle agglomeration and increasing luminescence via surface defect passivation

RSC Advances ◽  
2019 ◽  
Vol 9 (50) ◽  
pp. 28946-28952 ◽  
Author(s):  
Lenka Procházková ◽  
Vojtěch Vaněček ◽  
Václav Čuba ◽  
Radek Pjatkan ◽  
Rosana Martinez-Turtos ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Luminescence Intensity ◽  
Surface Defect ◽  
Core Shell ◽  
Particle Agglomeration ◽  
Defect Passivation ◽  
The Cost

Heat treatment is needed to increase the luminescence intensity of ZnO:Ga particles, but it comes at the cost of higher particle agglomeration.

scholarly journals Upgrading of methylammonium lead halide perovskite layers by thermal imprint

2021 ◽  
Vol 127 (4) ◽  
Author(s):  
Andre Mayer ◽  
Neda Pourdavoud ◽  
Zineb Doukkali ◽  
Kai Brinkmann ◽  
Johannes Rond ◽  
...  
Keyword(s):  
Layer Formation ◽  
Large Area ◽  
Perovskite Layer ◽  
Solvent Engineering ◽  
Lead Bromide ◽  
The Status ◽  
Lead Source ◽  
Conventional Solution ◽  
The Impact ◽  
Lead Halide

AbstractThe manufacturing of devices from methylammonium-based perovskites asks for reliable and scalable processing. As solvent engineering is not the option of choice to obtain homogeneous layers on large areas, our idea is to ‘upgrade’ a non-perfect pristine layer by recrystallization in a thermal imprint step (called ‘planar hot pressing’) and thus to reduce the demands on the layer formation itself. Recently, imprint has proven both its capability to improve the crystal size of perovskite layers and its usability for large area manufacturing. We start with methylammonium lead bromide layers obtained from a conventional solution-based process. Acetate is used as a competitive lead source; even under perfect conditions the resulting perovskite layer then will contain side-products due to layer formation besides the desired perovskite. Based on the physical properties of the materials involved we discuss the impact of the temperature on the status of the layer both during soft-bake and during thermal imprint. By using a special imprint technique called ‘hot loading’ we are able to visualize the upgrade of the layer with time, namely a growth of the grains and an accumulation of the side-products at the grain boundaries. By means of a subsequent vacuum exposition we reveal the presence of non-perovskite components with a simple inspection of the morphology of the layer; all experiments are supported by X-ray and electron diffraction measurements. Besides degradation, we discuss recrystallization and propose post-crystallization to explain the experimental results. This physical approach towards perovskite layers with large grains by post-processing is a key step towards large-area preparation of high-quality layers for device manufacturing.

Sign in / Sign up

Export Citation Format

Share Document