Riming Electrification as a Charge Generation Mechanism in Thunderstorms

1978 ◽  
Vol 35 (8) ◽  
pp. 1536-1548 ◽  
Author(s):  
Tsutomu Takahashi
Keyword(s):  
Generation Mechanism ◽  
Charge Generation ◽  
A Charge

Efficiency Enhancement of Tandem Organic Light-Emitting Devices Fabricated Utilizing an 1,4,5,8,9,11-Hexaazatriphenylene-Hexacarbonitrile Charge-Generation Layer

2015 ◽  
Vol 15 (10) ◽  
pp. 7717-7721
Author(s):  
Young Pyo Jeon ◽  
Tae Whan Kim
Keyword(s):  
Current Density ◽  
Efficiency Enhancement ◽  
Charge Generation ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Organic Light ◽  
Maximum Current ◽  
Organic Light Emitting Devices ◽  
Generation Mechanisms ◽  
A Charge

The electrical and the optical properties of tandem organic light-emitting devices (OLEDs) with stacked electroluminescence units were investigated to clarify the charge-generation mechanisms due to the existence of a charge-generation layer (CGL). The current density of the current limited devices with an 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN) CGL was 35% higher than that of devices with a tungsten-oxide (WO3) CGL. The maximum current density of the current limited devices with a HAT-CN CGL was as high as 259 mA/cm2. The brightness of the tandem OLEDs with a HAT-CN CGL was 15% higher than that of the tandem OLEDs with a WO3 CGL due to an increase in the current density. The charge-generation mechanisms of tandem OLEDs with a CGL were described on the basis of the experimental results.

Optimization of Electrical Output in Response to Mechanical Input in Piezoceramic Laminated Shells

Aerospace ◽  
2003 ◽  
Author(s):  
Amita D. Danak ◽  
Hwan-Sik Yoon ◽  
Gregory N. Washington
Keyword(s):  
Lead Zirconate Titanate ◽  
Material Properties ◽  
Piezoelectric Ceramic ◽  
Mechanical Strain ◽  
Lead Zirconate ◽  
Charge Generation ◽  
Laminated Shells ◽  
Parametric Studies ◽  
A Charge ◽  
Deformation Relationship

The piezoelectric ceramic, Lead Zirconate Titanate (PZT), is capable of producing large voltages in response to an applied mechanical stress when employed in a laminate manufactured using the THUNDER process. This study addresses the issue of optimizing mechanical parameters in a PZT unimorph to maximize charge generated due to mechanical strain. The PZT unimorph structure is initially curved and generates a surface charge when vertically loaded. In the analysis, the principles of shallow shell and linear piezoelectric laminate theories are employed to obtain an expression for charge in terms of geometry, material properties and loading. Analytical relationships are then derived that can be used to optimize the charge produced from these generators. Numerical parametric studies are then conducted to maximize the charge generation by manipulating dimensions of the components. Experimental results show a “convergence” to a theoretically predicted ‘applied force vs. deformation’ relationship when the PZT unimorph is subjected to a pressure load. Finally, a charge collecting circuitry for harvesting the charge produced is designed and presented.

Generation of electric charge associated with the formation of soft hail in thunderclouds

1961 ◽  
Vol 260 (1303) ◽  
pp. 537-549 ◽  
Keyword(s):  
Impact Velocity ◽  
Air Temperature ◽  
Temperature Difference ◽  
Temperature Drop ◽  
Ice Crystals ◽  
Drop Diameter ◽  
Charge Generation ◽  
Typical Experiment ◽  
A Charge ◽  
Negative Sense

The electrical charging which results from collisions between ice crystals and a simulated hailstone is measured as a function of their temperature difference, and of the size and impact velocity of the crystals. It is found that the sign of the charging is governed by that of the temperature difference, the hailstone becoming negatively charged if it is warmer than the rebounding crystals. The magnitude of the charging is proportional to the temperature differ­ence but rather insensitive to the size and impact velocity of the crystals. With a temperature difference of 5°C, a rebounding crystal of diameter about 50 μ produces, on average, a charge of 5 x 10 -9 e. s. u. The electrification of an artificial pellet of soft hail growing by the accretion of supercooled water droplets (riming) is also investigated. Freezing of the droplets on the hailstone is accompanied by the ejection of positively charged ice splinters, the hailstone acquiring a negative charge. The manner in which the rates of charging and splinter produc­tion vary with the air temperature, drop diameter and impact velocity has been established. In a typical experiment, with the air temperature at -15°C, droplets of diameter 80 μ impacting at 10 m s -1 freeze to produce, on average, 12 splinters and a charge of 4 x 10 -6 e. s. u. per drop. Droplets of diameter less than 30 μ produce few splinters and little charging. The results of both sets of experiments are interpreted in terms of the authors’ theory of charge separation in ice under the influence of a temperature gradient, and are used to calculate probable rates of charge generation in thunderstorms. It appears that the electrification which accompanies the growth of pellets of soft hail through the freezing and splintering of supercooled droplets is capable of generating and separating charge at the required rate of about 1 C km -3 min -1 but, while rebounding ice crystals will usually charge the hailstones in the same (negative) sense, this mechanism will contribute only slightly to thunderstorm electrification.

Charge generation mechanism in organic solar cells

2014 ◽  
Vol 16 (38) ◽  
pp. 20277-20278 ◽  
Author(s):  
Maria Antonietta Loi ◽  
Alessandro Troisi
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Generation Mechanism ◽  
Charge Generation

Two stacked tandem white organic light-emitting diodes employing WO3 as a charge generation layer

2016 ◽  
Author(s):  
Jong-Kwan Bin ◽  
Na Yeon Lee ◽  
SeungJae Lee ◽  
Bomin Seo ◽  
JoongHwan Yang ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Charge Generation ◽  
Light Emitting ◽  
Organic Light ◽  
A Charge

Photovoltaic Effect in Multilayer Organic Systems

1999 ◽  
Vol 598 ◽  
Author(s):  
G. Meinhardt ◽  
E. Moderegger ◽  
R. Schröder ◽  
G. Winter ◽  
M. Hanack ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Organic Materials ◽  
Copper Phthalocyanine ◽  
Photovoltaic Effect ◽  
Large Area ◽  
Charge Generation ◽  
Organic Layers ◽  
Organic Systems ◽  
Homo And Lumo ◽  
A Charge

ABSTRACTThe organic materials presented here, e.g. cyano-ether-PPV, different bisarylamidine-perylenes and conventional as well as substituted forms of phthalocyanines exhibit the advantages of low processing costs and the simplicity of tuning their optical properties. Hence they are promising candidates to be used in large area photovoltaic applications. The investigated cells consist of one or two organic layers sandwiched between electrodes of indium tin oxide (ITO) and aluminum. The experimental techniques of electroabsorption(EA)- spectroscopy, photocurrent-action spectroscopy and current voltage characterization were used to gain further insight into the process of charge generation, charge separation and transport of the charged species to the electrodes. To enhance the quantum efficiencies of the photovoltaic cells, combinations of organic materials with electron-accepting and electron- donating properties in multilayer devices were investigated. We chose the organic materials copper-phthalocyanine and a bisarylamidineperylene whose HOMO and LUMO level alignment should favor a charge transfer process in order to increase the photocurrent(PC) responsivity by enhanced exciton dissociation. Additionally, one of the two layers of a double layer device was blended with small amounts of the material constituting the second layer to further increase charge carrier generation by extending the dissociation zone.

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