Spectral Response of a-Si:H p-i-n Solar Cells Degraded by Blue and Red Light

1995 ◽  
Vol 377 ◽  
Author(s):  
A. Mittiga ◽  
L. Mariuc ◽  
T. Fasolino ◽  
A. Romano ◽  
P. Fiorini ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Spatial Distribution ◽  
Solar Cells ◽  
Blue Light ◽  
Spectral Response ◽  
Red Light ◽  
Experimental Results ◽  
Simulation Program ◽  
Total Density ◽  
Response Curves

ABSTRACTWe have degraded a-Si:H p-i-n solar cells at Voc using both red and blue light to investigate the effect of a possible different spatial distribution of defects in the intrinsic layer. We have found that the I-V and the spectral response curves of the degraded cells depend on the total density of defects only and are not sensitive to the wavelength of the degradation light. These experimental results and some peculiar features of the spectral response of the degraded cells are explained with the aid of a numerical simulation program.

scholarly journals Photosynthetic Physiology of Blue, Green, and Red Light: Light Intensity Effects and Underlying Mechanisms

2021 ◽  
Vol 12 ◽  
Author(s):  
Jun Liu ◽  
Marc W. van Iersel
Keyword(s):  
Blue Light ◽  
Interactive Effect ◽  
Red Light ◽  
Green Light ◽  
Photosynthetic Photon Flux Density ◽  
Interactive Effects ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Light Spectrum ◽  
Response Curves

Red and blue light are traditionally believed to have a higher quantum yield of CO2 assimilation (QY, moles of CO2 assimilated per mole of photons) than green light, because green light is absorbed less efficiently. However, because of its lower absorptance, green light can penetrate deeper and excite chlorophyll deeper in leaves. We hypothesized that, at high photosynthetic photon flux density (PPFD), green light may achieve higher QY and net CO2 assimilation rate (An) than red or blue light, because of its more uniform absorption throughtout leaves. To test the interactive effects of PPFD and light spectrum on photosynthesis, we measured leaf An of “Green Tower” lettuce (Lactuca sativa) under red, blue, and green light, and combinations of those at PPFDs from 30 to 1,300 μmol⋅m–2⋅s–1. The electron transport rates (J) and the maximum Rubisco carboxylation rate (Vc,max) at low (200 μmol⋅m–2⋅s–1) and high PPFD (1,000 μmol⋅m–2⋅s–1) were estimated from photosynthetic CO2 response curves. Both QYm,inc (maximum QY on incident PPFD basis) and J at low PPFD were higher under red light than under blue and green light. Factoring in light absorption, QYm,abs (the maximum QY on absorbed PPFD basis) under green and red light were both higher than under blue light, indicating that the low QYm,inc under green light was due to lower absorptance, while absorbed blue photons were used inherently least efficiently. At high PPFD, the QYinc [gross CO2 assimilation (Ag)/incident PPFD] and J under red and green light were similar, and higher than under blue light, confirming our hypothesis. Vc,max may not limit photosynthesis at a PPFD of 200 μmol m–2 s–1 and was largely unaffected by light spectrum at 1,000 μmol⋅m–2⋅s–1. Ag and J under different spectra were positively correlated, suggesting that the interactive effect between light spectrum and PPFD on photosynthesis was due to effects on J. No interaction between the three colors of light was detected. In summary, at low PPFD, green light had the lowest photosynthetic efficiency because of its low absorptance. Contrary, at high PPFD, QYinc under green light was among the highest, likely resulting from more uniform distribution of green light in leaves.

Band Discontinuity Effect on a-Si:H and a-SiGe:H Solar Cells

1995 ◽  
Vol 377 ◽  
Author(s):  
X. Xu ◽  
A. Banerjee ◽  
J. Yang ◽  
S. Guha ◽  
K. Vasanth ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Solar Cells ◽  
Solar Cell ◽  
Valence Band ◽  
Cell Performance ◽  
Experimental Results ◽  
Microcrystalline Silicon ◽  
Solar Cell Performance ◽  
Single Junction ◽  
P Type

ABSTRACTThe electrical bandgap of microcrystalline silicon (μc-Si:H) p type layers used in a-Si:H alloy solar cells and the band edge discontinuities between μc-Si:H and a-Si:H alloys have been determined by internal photoemission measurements. The bandgap of μc-Si:H is found to be in the range of 1.50 to 1.57 eV, and the discontinuities at the conduction and the valence band edges are 0 to 0.07 and 0.26 to 0.35 eV, respectively. Use of these parameters in the numerical simulation of single-junction a-Si:H and a-SiGe:H alloy solar cells is found to predict experimental results of solar cell performance.

Design and Growth of Band-GAP Graded a-SiGe:H Solar Cells

1995 ◽  
Vol 377 ◽  
Author(s):  
K. Vasanth ◽  
A. Payne ◽  
B. Crone ◽  
S. Sherman ◽  
M. Jakubowski ◽  
...  
Keyword(s):  
Solar Cells ◽  
Amorphous Silicon ◽  
Band Gap ◽  
Triple Junction ◽  
Cell Parameter ◽  
Red Light ◽  
Experimental Results ◽  
Buffer Layers ◽  
Silicon Solar Cells ◽  
Device Design

ABSTRACTThe i-layers of the middle and bottom cells in stable triple-junction amorphous silicon solar cells are composed of a-SiGe:H alloys which are graded in composition to enhance performance. We compare modeling and experimental results for three i-layer band gap grading schemes to determine the optimal profile. We find a good correlation between model trends and measured device parameters for all grading schemes. This is encouraging for the use of the model in predictive device design. We find that the highest white and red light performance do not necessarily have the same cell parameter set. Modeling and experiment indicate that thin cells without band gap profile and with suitably designed p/i and n/i buffer layers, have the best red light performance.

Fabrication and Optimization of a-Si:H n-i-p Single-junction Solar Cells with 8 Å/s Intrinsic Layers of Protocrystalline Si:H Materials

2007 ◽  
Vol 989 ◽  
Author(s):  
Xinmin Cao ◽  
Wenhui Du ◽  
Y. Ishikawa ◽  
Xianbo Liao ◽  
Robert W. Collins ◽  
...  
Keyword(s):  
Solar Cells ◽  
Blue Light ◽  
Spectral Response ◽  
Light Response ◽  
Open Circuit ◽  
System A ◽  
Hydrogen Dilution ◽  
Blue Light Response ◽  
Current Voltage ◽  
The University

AbstractAt the University of Toledo (UT), we have investigated hydrogenated amorphous silicon (a-Si:H) n-i-p solar cells with intrinsic layers deposited at high rates, ~ 8 Å/s, using our UT multi-chamber load-locked PECVD system. a-Si:H i-layers were grown with a VHF plasma density of ~ 0.2 W/cm2 and a frequency of 70 MHz using various hydrogen dilution levels. It is observed from the current-voltage (I-V) device performance characteristics that the open-circuit voltage (Voc) increases with increasing hydrogen dilution reaching a maximum and then decreasing. This drop in Voc can be attributed to the transition region (or protocrystalline regime) from an amorphous phase into a mixed amorphous+nanocrystalline (a + nc) phase for the i-layer. An initial efficiency of 9.99% (Voc = 0.986 V, Jsc = 13.98 mA/cm2, FF = 72.5%) was obtained. Quantum efficiency (QE) measurement has shown that the blue light response increases as the hydrogen dilution increases. Very good blue light spectral response with QE values over 0.7 at the wavelength of 400 nm have been obtained for a-Si:H cells made under specific deposition conditions in which tailored protocrystalline silicon materials were incorporated at the i/p interface region.

scholarly journals Down-Conversion Polymer Composite Coatings with Multipeak Absorption and Emission

Coatings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 282
Author(s):  
Jun Fang ◽  
Wenting Liu ◽  
Wenying Zhou ◽  
Cheng Zhu ◽  
Yaru Ni ◽  
...  
Keyword(s):  
Solar Cells ◽  
Uv Light ◽  
Spectral Response ◽  
Composite Coatings ◽  
Red Light ◽  
Polymer Coatings ◽  
Absorption And Emission ◽  
Response Range ◽  
Luminescent Coatings ◽  
Down Conversion

Spectral adjustment is an effective method to increase light conversion efficiency of solar cells and to promote the growth of plants. Down-converter (DC) materials are considered to be one of the most effective methods of spectral modification. The focus of this work was to expand the spectral response range of down-conversion layers to achieve multipeak absorption and emission. Sr2CaMoO6:Sm,Na and YVO4:Bi,Eu, which have different excitation peaks in the UV-blue region and varied emission peaks in visible light regions, were prepared in this work. Sr2CaMoO6:Sm,Na can effectively produce red light at 648 nm upon excitation at 408 nm, while YVO4:Bi,Eu can produce red light at 618 nm upon excitation at 365 nm. Polymeric luminescent coatings with one single kind of phosphor were prepared separately before the two phosphors were mixed together in uniform polymer coatings. The two phosphors were also assembled in bilayer coatings with different concentrations. The results showed that high transmittances over 90% were achieved for the two composite coatings with the thickness of 20 and 30 μm. The increase in particle loadings from 1‰ to 4‰ slightly decreased coating transmittance but increased luminescence intensity. The increase in the ratio of Sr2CaMoO6:Sm,Na and YVO4:Bi,Eu from 5/1 to 10/1 resulted in high transmittance of the DC coatings, independent of total filler loadings (3‰ and 4‰) and coating thickness. The relative intensities of emission peaks can be adjusted conveniently by changing filler ratios. In addition, the transmittance and luminescent intensities of the coatings where the two phosphors were assembled in two layers were close to the uniform coatings, suggesting the negligible effect of UV light irradiation order. This work proved that the prepared coatings presented multipeak absorption and emission upon UV light excitation. These coatings can be expected to be applied in fields such as solar cells and agriculture greenhouses.

scholarly journals Numerical Simulation Study on Flow and Fracture of Granular Materials

2019 ◽  
Vol 2019 ◽  
pp. 1-19
Author(s):  
Mingqing Liu ◽  
Jun Liu ◽  
Guangkun Liu ◽  
Peng Shan ◽  
Zhimin Xiao ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Granular Materials ◽  
Numerical Algorithm ◽  
Fracture Process ◽  
Particle System ◽  
Experimental Results ◽  
Simulation Program ◽  
Granular System ◽  
Exploratory Stage ◽  
The Relationship

Flow and fracture of granular materials under external loads is a complex mechanical process, and the research on its law is still in the exploratory stage. In this paper, the flow and fracture law of granular materials is taken as the research object, and numerical algorithm compilation and program development are combined to study. Taking full advantage of the existing algorithms and developing new ones based on the existing DEM theory, a numerical simulation program for the flow and fracture of granular materials is developed. The flow and fracture process of concrete spherical granular system with diameter of 4 cm under loading rate of 70 mm/min and end of loading of 50 kN is taken as an example to verify the simulation program. At the same time, the loading experiment of the concrete spherical particle system under the same simulation conditions was also carried out. The simulation results are compared with the experimental results in three aspects: the generation location of the particle system, the relationship between the whole load and displacement, and the degree of particle breakage. The results show that the numerical simulation is in good agreement with the experimental results, which verifies the reliability of the numerical algorithm and the simulation program, and can provide support for the study of the flow and fracture process of granular materials.

Amorphous Silicon Three Color Detector

1995 ◽  
Vol 377 ◽  
Author(s):  
H. Stiebig ◽  
J. Giehl ◽  
D. Knipp ◽  
P. Rieve ◽  
M. Böhm
Keyword(s):  
Amorphous Silicon ◽  
Analytical Model ◽  
Integrated Circuit ◽  
Dynamic Range ◽  
Circuit Simulation ◽  
Spectral Response ◽  
Simulation Program ◽  
Response Curves ◽  
Pool Model ◽  
Color Sensors

ABSTRACTBand gap and defect engineered amorphous silicon based nipin photo diodes with bias controlled spectral response have been fabricated successfully. The devices exhibit good linearity over a wide illumination range and linearly independent spectral response curves which are required to generate a standard RGB-signal. In the bias range from -1.5 V to 1.5 V a dynamic range exceeding 90 dB for two color sensors and 80 dB for three color sensors has been observed. The general operation principle of the multispectral photo diode is discussed using a numerical simulation program. The model describes the defect state distribution of dangling bonds according to the defect-pool model and uses coherent wave propagation in the device to calculate the profile of photo generated carriers. Additionally, an analytical model has been developed to be included into standard circuit simulation programs like SPICE (Simulation Program with Integrated Circuit Emphasis). The analytical model uses linear field approximations in both i-layers of the device.

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