Critical Concentrations of Atmospheric Contaminants in a-Si:H and μc-Si:H Solar Cells

2010 ◽  
Vol 1245 ◽  
Author(s):  
Tsvetelina Merdzhanova ◽  
Jan Woerdenweber ◽  
Thilo Kilper ◽  
Helmut Stiebig ◽  
Wolfhard Beyer ◽  
...  
Keyword(s):  
Solar Cells ◽  
Oxygen Concentration ◽  
Short Circuit ◽  
Red Light ◽  
Chamber Wall ◽  
Light Illumination ◽  
Critical Concentrations ◽  
Process Gas ◽  
Critical Oxygen ◽  
Critical Oxygen Concentration

AbstractWe report on a direct comparison of the effect of the atmospheric contaminants on a-Si:H and μc-Si:H p-i-n solar cells deposited by plasma-enhanced chemical vapor deposition (PECVD) at 13.56 MHz. Nitrogen and oxygen were inserted by two types of controllable contamination sources: (i) directly into the plasma through a leak at the deposition chamber wall or (ii) into the process gas supply line. Similar critical concentrations in the range of 4-6×1018 cm-3 for nitrogen and 1.2-5×1019 cm-3 for oxygen were observed for both a-Si:H and μc-Si:H cells for the chamber wall leak. Above these critical concentrations the solar cell efficiency decreases for a-Si:H solar cells due to losses in the fill factor under red light illumination (FFred). For μc-Si:H cells the losses in FFred and in short-circuit current density deteriorate the device performance. Only for a-Si:H the critical oxygen concentration is found to depend on the contamination source. Conductivity measurements suggest that at the critical oxygen concentration the Fermi level is located about 0.05 eV above midgap for both a-Si:H and μc-Si:H.

scholarly journals Critical oxygen concentration in hydrogenated amorphous silicon solar cells dependent on the contamination source

2010 ◽  
Vol 96 (10) ◽  
pp. 103505 ◽  
Author(s):  
Jan Woerdenweber ◽  
Tsvetelina Merdzhanova ◽  
Helmut Stiebig ◽  
Wolfhard Beyer ◽  
Aad Gordijn
Keyword(s):  
Solar Cells ◽  
Amorphous Silicon ◽  
Oxygen Concentration ◽  
Hydrogenated Amorphous Silicon ◽  
Silicon Solar Cells ◽  
Contamination Source ◽  
Critical Oxygen ◽  
Critical Oxygen Concentration ◽  
Hydrogenated Amorphous

High critical oxygen concentration in microcrystalline silicon solar cells

2010 ◽  
Vol 4 (11) ◽  
pp. 323-325 ◽  
Author(s):  
Tsvetelina Merdzhanova ◽  
Jan Woerdenweber ◽  
Wolfhard Beyer ◽  
Uwe Zastrow ◽  
Helmut Stiebig ◽  
...  
Keyword(s):  
Solar Cells ◽  
Oxygen Concentration ◽  
Silicon Solar Cells ◽  
Microcrystalline Silicon ◽  
Critical Oxygen ◽  
Critical Oxygen Concentration

Electronic Properties of Polymer-Fullerene Solar Cells

2001 ◽  
Vol 665 ◽  
Author(s):  
V. Dyakonov ◽  
I. Riedel ◽  
C. Deibel ◽  
J. Parisi ◽  
C. J. Brabec ◽  
...  
Keyword(s):  
Solar Cells ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Fill Factor ◽  
Short Circuit ◽  
Open Circuit ◽  
Light Illumination ◽  
Positive Temperature ◽  
Admittance Spectroscopy ◽  
Spin Resonance

ABSTRACTWe studied the electronic transport properties of conjugated polymer/fullerene based solar cells by means of temperature and illumination intensity dependent current-voltage characteristics, admittance spectroscopy and light-induced electron spin resonance. The short-circuit current density increases with temperature at all light illumination intensities applied, i.e., from 100 mW/cm2 to 0.1 mW/cm2 (white light), whereas a temperature independent behavior was expected. An increase of the open-circuit voltage from 850 mV to 940 mV was observed, when cooling down the device from room temperature to 100 K. The fill factor depends strongly on temperature with a positive temperature coefficient in the whole temperature range. In contrast, the light intensity dependence of the fill factor shows a maximum of 52% at intermediate illumination intensities (3 mW/cm2) and decreases subsequently, when increasing the intensity up to 100 mW/cm2. Further studies by admittance spectroscopy revealed two frequency dependent contributions to the device capacitance. One, as we believe, originates from trapping states located at the interface between composite and metal electrode with an activation energy of EA=180 meV, and the other one is from very shallow bulk states with EA=10 meV. The origin of the latter is possibly the thermally activated conductivity. The photo-generation of charge carriers and their fate in these blends have been studied by light-induced electron spin resonance. We can clearly distinguish between photo-generated electrons and holes in the composites due to different spectroscopic splitting factors (g-factors). Additional information on the environmental axial symmetry of the holes located on the polymer chains as well as on a lower, rhombic, symmetry of the electrons located on the methanofullerene molecules has been obtained. The origin of the signals and parameters of the g-tensor have been confirmed from studies on a hole doped polymer.

Role of Critical Oxygen Concentration in the β-Li3PS4–xOx Solid Electrolyte

2022 ◽  
Author(s):  
Swastika Banerjee ◽  
Manas Likhit Holekevi Chandrappa ◽  
Shyue Ping Ong
Keyword(s):  
Solid Electrolyte ◽  
Oxygen Concentration ◽  
Critical Oxygen ◽  
Critical Oxygen Concentration

Factors Influencing Submergence and the Heart Rate in the Frog

1964 ◽  
Vol 41 (2) ◽  
pp. 417-431
Author(s):  
D. R. JONES
Keyword(s):  
Carbon Dioxide ◽  
Heart Rate ◽  
Oxygen Concentration ◽  
Carbon Dioxide Concentration ◽  
Carbon Dioxide Content ◽  
Factors Influencing ◽  
Critical Oxygen ◽  
Critical Oxygen Concentration ◽  
Main Factors ◽  
Critical Carbon Dioxide

1. The ability of the frog to remain submerged declines as the oxygen concentration in the water falls or the carbon dioxide content rises. The critical oxygen concentration appears to be about 5 mg./l. and the critical carbon dioxide concentration 100 mg./l. at temperatures around 10° C. 2. Submergence results in a decrease in heart rate which develops over a period of 15-30 min. but which disappears immediately the animal surfaces and breathes. The bradycardia is accentuated by oxygen lack or carbon dioxide excess. 3. During submergence the heart is influenced by two main factors, the shortage of oxygen and the cessation of breathing movements, both of which contribute to the decrease in rate. The former can still affect rate after vagotomy. The connexion between breathing and heart rate is dependent on the nervous system, though the detailed pathway is not worked out.

Effect of White and Red Light Illumination on the Degradation of a-Si:H Solar Cells

1995 ◽  
Vol 377 ◽  
Author(s):  
Taraneh Jamali-Beh ◽  
I.-S Chen ◽  
H. Liu ◽  
Y. Lee ◽  
C. R. Wronski
Keyword(s):  
Solar Cells ◽  
Uniform Distribution ◽  
Quantum Efficiency ◽  
Red Light ◽  
Empirical Relation ◽  
Light Illumination ◽  
Light Sources ◽  
Charged Defect ◽  
Halogen Light ◽  
Induced Defects

ABSTRACTStructures were carried out on the degradation of heterojunction and homojunction a-Si:H solar cells, using Xenon arc and tungsten halogen light sources. The degradations were carried out with both white and red light with the intensities being calibrated using the saturated reverse biased photocurrents. Because of the different light intensities, I, involved, comparisons between the different illumination were made after exposure times, t, where I1.8t = constant. The degraded states of the cells were characterized with light I-V, dark I-V, and quantum efficiency measurements. The same degraded states, as indicated by the all three characteristics, are obtained with either white and red light providing the intensities are calibrated using the actual p-i-n cells. It is also found that the empirical relation for obtaining the same degradation found by L. Yang holds for these illuminations being about 1 and 10 suns. Analysis of the dark I-V's using AMPS with a charged defect distributions of defects indicates that with the exposures used, the light induced defects have a close to uniform distribution throughout the i-layer.

Preparation of Microcrystalline Silicon Based Solar Cells at High i-layer Deposition Rates Using a Gas Jet Technique

2000 ◽  
Vol 609 ◽  
Author(s):  
S.J. Jones ◽  
R. Crucet ◽  
X. Deng ◽  
D.L. Williamson ◽  
M. Izu
Keyword(s):  
Solar Cells ◽  
Short Circuit ◽  
Red Light ◽  
Layer Growth ◽  
Gas Jet ◽  
Similar Amount ◽  
Microcrystalline Silicon ◽  
Deposition Rates ◽  
Silicon Based ◽  
Microcrystalline Materials

ABSTRACTA Gas Jet technique has been used to prepare microcrystalline silicon (μc-Si) thin films at deposition rates as high as 20 Å/s. The films have microcrystal sizes between 80 and 120 Å with a heterogeneous microstructure containing regions with columnar growth and other regions with a more randomly oriented microstructure. These materials have been used as i-layers for nip single-junction solar cells. The high deposition rates allow for fabrication of the required thicker μc-Si i-layers in a similar amount of time to those used for high quality a-SiGe:H i-layers (rates of 1-3 Å/s). Using a 610nm cutoff filter which only allows red light to strike the device, pre-light soaked short circuit currents of 8-10 mA/cm2 and 2.7% red-light efficiencies have been obtained while AM1.5 white light efficiencies are above 7%. These efficiencies are higher than those typically obtained for μc-Si cells prepared at the high i-layer growth rates using other deposition techniques. After 1000 h. of light soaking, the efficiencies on average degrade only by 2-5% (stabilized efficiencies of 2.6%) consistent with the expected high stability with the microcrystalline materials. The small amount of degradation compares with the 15-17% degradation in efficiencies for a-SiGe:H cells subjected to similar irradiation treatments (final light-soaked red light efficiencies of 3.2%). Improvements in the cell efficiencies may come through an understanding of the role that columnar microstructure and void structure plays in determining the device performance.

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