Analysis of Fill Factor Losses in a-Si and a-SiGe Alloy Solar Cells Using a New Technique

1995 ◽  
Vol 377 ◽  
Author(s):  
A. Banerjee ◽  
X. Xu ◽  
J. Yang ◽  
S. Guha
Keyword(s):  
Solar Cells ◽  
Amorphous Silicon ◽  
Fill Factor ◽  
New Technique ◽  
Light Illumination ◽  
Single Junction ◽  
Current Collection ◽  
Sige Alloy ◽  
Back Reflectors ◽  
A New Technique

ABSTRACTA new technique to diagnose fill factor losses occurring in single-junction amorphous silicon (a-Si) alloy based nip solar cells has been explored. The method consists of the measurements of the fill factor of the device under blue and red light illumination and the current-collection loss obtained from the ratio of the quantum efficiency versus wavelength spectra at zero and reverse bias. Normally, the losses are higher at low and high wavelengths. It has been observed that there is a strong correlation between the values of the blue and red fill factors and the current collection losses at the pli interfaces and the bulk of the i-layer, respectively. The losses have been attributed to back diffusion of carriers at the pli interface and to the bulk of the i-Layer. There is a sensitive dependence between these losses and the texture of the substrate: textured substrates lead to higher losses compared to specular substrates. The technique has been used successfully to enhance the values of the red, blue, and AM 1.5 fill factors of both a-Si and amorphous silicon-germanium (a-SiGe) alloy single-junction cells on back reflectors by the optimization of device fabrication parameters. The optimized cells on textured back reflectors exhibit reduced losses. The paper presents an analysis of the experimental results.

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.

Light Propagation in Flexible Thin-Film Amorphous Silicon Solar Cells with Nanotextured Metal Back Reflectors

2020 ◽  
Vol 12 (23) ◽  
pp. 26184-26192 ◽  
Author(s):  
Shuangying Cao ◽  
Dongliang Yu ◽  
Yinyue Lin ◽  
Chi Zhang ◽  
Linfeng Lu ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Amorphous Silicon ◽  
Light Propagation ◽  
Silicon Solar Cells ◽  
Back Reflectors ◽  
Metal Back

Effect of Excitation Frequency on the Performance of Amorphous Silicon Alloy Solar Cells

1998 ◽  
Vol 507 ◽  
Author(s):  
J. Yang ◽  
S. Sugiyama ◽  
S. Guha
Keyword(s):  
Solar Cells ◽  
Glow Discharge ◽  
Amorphous Silicon ◽  
Excitation Frequency ◽  
Deposition Rates ◽  
Solar Cell Performance ◽  
Single Junction ◽  
Silicon Alloy ◽  
Double Junction ◽  
Junction Structure

ABSTRACTWe have studied amorphous silicon alloy solar cells made by using a modified-very-highfrequency glow discharge at 75 MHz with a deposition rate of ∼6 Å/s. The solar cell performance is compared with those made from conventional glow discharge at 13.56 MHz with lower deposition rates. Cells made at ∼6 Å/s with 75 MHz showed comparable stabilized efficiency to those made at ∼3 Å/s with 13.56 MHz. The best performance, however, was obtained with ∼1 Å/s, including a stabilized 9.3% a-Si alloy single-junction cell employing conventional glow discharge technique. Using 75 MHz, we have achieved 11.1% and 10.0% initial active-area efficiencies for a-Si alloy and a-SiGe alloy n i p cells, respectively. An initial efficiency of 11.0% has also been obtained in a dual bandgap double-junction structure.

Structural Defects in thin Film Amorphous Silicon Films Deposited on Textured TCO Material

1995 ◽  
Vol 377 ◽  
Author(s):  
D. Knoesen ◽  
R. E. I. Schropp ◽  
W. F. Van Der Weg
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Surface Morphology ◽  
Amorphous Silicon ◽  
Layer Thickness ◽  
Fill Factor ◽  
Type A ◽  
Structural Defects ◽  
Cross Sectional ◽  
Structure And Morphology

ABSTRACTA cross sectional TME study has been conducted into the structure and morphology of p- and i-type a-Si:H layers of device quality deposited on textured TCO on glass. The layer thickness over peaks is shown to be equivalent to that for flat regions, while defective regions are found in narrow valleys, initiating from the pit of the valleys. These regions may act as regions of excessive recombination and/or shunting regions, thus leading to a reduced Voc and fill factor in thin solar cells. A cosine relationship was found between the deposited thickness and the facet angles of the surface TCO crystals. It is concluded that for best performance of the deposited layer, the deposition has to be completely isotropie, and that the preferred surface morphology of textured TCO be sharp peaks with wider valleys.

Improvement of Single-Junction a-Si:H Thin-Film Solar Cells Toward 10% Efficiency

2011 ◽  
Vol 1321 ◽  
Author(s):  
P. H. Cheng ◽  
S. W. Liang ◽  
Y. P. Lin ◽  
H. J. Hsu ◽  
C. H. Hsu ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Amorphous Silicon ◽  
Chemical Vapor ◽  
Thin Film Solar Cells ◽  
Window Layer ◽  
Electron Hole ◽  
Single Junction ◽  
Boron Doped ◽  
Hydrogenated Amorphous

ABSTRACTThe hydrogenated amorphous silicon (a-Si:H) single-junction thin-film solar cells were fabricated on SnO2:F-coated glasses by plasma-enhanced chemical vapor deposition (PECVD) system. The boron-doped amorphous silicon carbide (a-SiC:H) was served as the window layer (p-layer) and the undoped a-SiC:H was used as a buffer layer (b-layer). The optimization of the p/b/i/n thin-films in a-Si:H solar cells have been carried out and discussed. Considering the effects of light absorption, electron-hole extraction and light-induced degradation, the thicknesses of p, b, n and i layers have been optimized. The optimal a-Si:H thin-film solar cell having an efficiency of 9.46% was achieved, with VOC=906 mV, JSC=14.42 mA/cm2 and FF=72.36%.

scholarly journals Internal electric field and fill factor of amorphous silicon solar cells

2010 ◽  
Author(s):  
Michael Stuckelberger ◽  
Arvind Shah ◽  
Janez Krc ◽  
Matthieu Despeisse ◽  
Fanny Meillaud ◽  
...  
Keyword(s):  
Solar Cells ◽  
Electric Field ◽  
Amorphous Silicon ◽  
Fill Factor ◽  
Silicon Solar Cells ◽  
Internal Electric Field

High efficiency amorphous and nanocrystalline silicon based multi-junction solar cells deposited at high rates on textured Ag/ZnO back reflectors

2009 ◽  
Vol 1153 ◽  
Author(s):  
Guozhen Yue ◽  
Laura Sivec ◽  
Baojie Yan ◽  
Jeff Yang ◽  
Subhendu Guha
Keyword(s):  
Solar Cells ◽  
Triple Junction ◽  
High Efficiency ◽  
Nanocrystalline Silicon ◽  
Open Circuit ◽  
Very High Frequency ◽  
Solar Cell Performance ◽  
Single Junction ◽  
Back Reflectors ◽  
Back Reflector

AbstractWe report our recent progress on nc-Si:H single-junction and a-Si:H/nc-Si:H/nc-Si:H triple-junction cells made by a modified very-high-frequency (MVHF) technique at deposition rates of 10-15 Å/s. First, we studied the effect of substrate texture on the nc-Si:H single-junction solar cell performance. We found that nc-Si:H single-junction cells made on bare stainless steel (SS) have a good fill factor (FF) of ˜0.73, while it decreased to ˜0.65 when the cells were deposited on textured Ag/ZnO back reflectors. The open-circuit voltage (Voc) also decreased. We used dark current-voltage (J-V), Raman, and X-ray diffraction (XRD) measurements to characterize the material properties. The dark J-V measurement showed that the reverse saturated current was increased by a factor of ˜30 when a textured Ag/ZnO back reflector was used. Raman results revealed that the nc-Si:H intrinsic layers in the two solar cells have similar crystallinity. However, they showed a different crystallographic orientation as indicated in XRD patterns. The material grown on Ag/ZnO has more random orientation than that on SS. These experimental results suggested that the deterioration of FF in nc-Si:H solar cells on textured Ag/ZnO was caused by poor nc-Si:H quality. Based on this study, we have improved our Ag/ZnO back reflector and the quality of nc-Si:H component cells and achieved an initial and stable active-area efficiencies of 13.4% and 12.1%, respectively, in an a-Si:H/nc-Si:H/nc-Si:H triple-junction cell.

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