Role of Bandgap Grading for the Performance of Microcrystalline Silicon Germanium Solar Cells

1999 ◽  
Vol 557 ◽  
Author(s):  
M. Krause ◽  
R. Carius ◽  
H. Stiebig ◽  
F. Finger ◽  
D. Lundszien ◽  
...  
Keyword(s):  
Solar Cells ◽  
Silicon Germanium ◽  
Near Infrared ◽  
Infrared Region ◽  
Open Circuit ◽  
Microcrystalline Silicon ◽  
Ir Detectors ◽  
Germanium Content ◽  
20 Nm ◽  
Graded Bandgap

AbstractThe optical absorption of microcrystalline silicon germanium alloys (μc-Si1-xGex:H) increases in the near infrared region with increasing germanium content. Therefore, these alloys are promising candidates for the application as intrinsic absorber material in thin film solar cells with tandem and triple structure or IR-detectors. The material properties for a germanium content (x) up to 0.6 and the performance of solar cells based on this material were investigated. Graded bandgap structures are used to optimize the cell performance. For cells with x > 0.3 a continuously graded bandgap in the rear 20 nm of the i-layer (at the i/n interface) results in an enhancement of the open circuit voltage by 40-80 mV compared to an abrupt bandgap discontinuity. When the design of the p/i interface region is changed in a similar way no effect on Voc is observed.

Near Infrared Detectors and Solar Cells Based on Microcrystalline Silicon Germanium

2000 ◽  
Vol 609 ◽  
Author(s):  
M. Krause ◽  
H. Stiebig ◽  
R. Carius ◽  
H. Wagner
Keyword(s):  
Gas Phase ◽  
Silicon Germanium ◽  
Infrared Detectors ◽  
Near Infrared ◽  
Infrared Region ◽  
Microcrystalline Silicon ◽  
Germanium Content ◽  
Cell Parameters ◽  
Hydrogen Dilution ◽  
Near Infrared Region

ABSTRACTMicrocrystalline silicon germanium alloys (ν-Si1−xGex:H) exhibit an enhanced optical absorption in the near infrared region with increasing germanium content. Therefore, the employment of this material as intrinsic absorber is a promising challenge for thin film technology in photovoltaics and sensorics. The influence of hydrogen dilution on the material and the performance of pin diodes prepared in a PECVD process with 10 % GeH4 in the gas phase is discussed. These results are compared with the characteristics of diodes prepared with higher germane content in the gas phase. With increasing germane content the solar cell parameters Voc and FF decrease and the deposition regime where good optoelectronic properties are observed is narrowed.

Optical and Photovoltaic Properties of CdS/Ag2S Quantum Dots Co-Sensitized-Solar Cells

2013 ◽  
Vol 761 ◽  
pp. 15-18 ◽  
Author(s):  
Auttasit Tubtimtae ◽  
Ming Way Lee
Keyword(s):  
Solar Cells ◽  
Quantum Dot ◽  
Near Infrared ◽  
Energy Gap ◽  
Photocurrent Density ◽  
Infrared Region ◽  
Open Circuit ◽  
Photovoltaic Properties ◽  
Different Characteristics ◽  
Sensitized Solar Cells

Subscript textWe present a co-sensitization of CdS/Ag2S quantum-dot as sensitizers for solar cells. The optical properties of single and double-layered quantum-dot conditions were monitored using UV-Vis spectrophotometer. The results show that the different characteristics of absorption spectra depended on the types of QDs, indicating to the different energy gap of each QDs deposited on TiO2 surface and the tunable absorption ranges of the sample of double-layered quantum-dot-sensitized TiO2 electrodes are broader and the absorption intensity are higher than the single-layered quantum-dot, attributed to the co-absorption of two QDs to the light and both CdS and Ag2S are activated in visible to near-infrared region (450-1100 nm). The photovoltaic data shows that the highest efficiency of 1.41% with a photocurrent density, Jsc of 20.6 mA/cm2, an open-circuit voltage, Voc of 0.32 V and a fill factor, FF of 21.3% were yielded by the sample of CdS(3)/Ag2S(4) as an optimum condition of dipping cycles for CdS and Ag2S under irradiance of 100 mW/cm2 (AM 1.5G).

Microcrystalline Silicon-Germanium Alloys for Absorption Layers in Thin Film Solar Cells

1998 ◽  
Vol 507 ◽  
Author(s):  
R. Carius ◽  
J. Fölsch ◽  
D. Lundszien ◽  
L. Houben ◽  
F. Finger
Keyword(s):  
Solar Cells ◽  
Silicon Germanium ◽  
Thin Film Solar Cells ◽  
Structural Quality ◽  
Microcrystalline Silicon ◽  
Germanium Content ◽  
Microscopic Scale ◽  
Infrared Spectral ◽  
A Cell ◽  
First Time

ABSTRACTThin microcrystalline silicon-germanium films (μ-Sil.xGex:H) prepared by PECVD at 95 MHz have been investigated. The optical absorption of these films increases in the infrared spectral region with increasing germanium content. In addition to the shift of the indirect gap an increase of the absorption coefficient above the band edge is observed. The material shows high crystallinity and exhibits good structural quality similar to pure μ-Si:H films. The films are homogeneous on a macroscopic to a microscopic scale as confirmed by Raman spectroscopy and Electron Microscopy methods. p-i-n solar cells with pc-Sil-xGex:H i-layers have been prepared for the first time. An efficiency of η = 3.1 % under AM1.5 has been obtained for a cell with 150 nm thin i-layer.

Effect of Bandgap Grading on the Performance of a-Si1-xGex:H Single-Junction Thin-Film Solar Cells

2011 ◽  
Vol 1321 ◽  
Author(s):  
H. J. Hsu ◽  
C. M. Wang ◽  
C. H. Hsu ◽  
C. C. Tsai
Keyword(s):  
Solar Cells ◽  
Silicon Germanium ◽  
Potential Gradient ◽  
Open Circuit ◽  
Hole Transport ◽  
Single Junction ◽  
Cell Efficiency ◽  
A Cell ◽  
20 Nm ◽  
Amorphous Silicon Germanium

ABSTRACTIn this work, the effect of bandgap grading of hydrogenated amorphous silicon germanium (a-Si1-xGex:H) absorber near the p/i and the i/n interfaces was investigated. The a-Si1-xGex:H single-junction solar cells were improved by applying both p/i grading and i/n grading. Our results showed that both the p/i and the i/n grading can increase the open-circuit voltage (VOC) as compared to the cell without grading. The i/n grading can further improve the FF. Presumably the potential gradient created by the i/n grading can facilitate the hole transport thus it can improve the FF. However, the JSC decreased as the i/n grading width increased. The reduction of JSC was due to the loss in the red response, which can be attributed to the replacement of lower bandgap material by the larger ones. Combining the effects of VOC, JSC and FF, a suitable thickness of the p/i and the i/n grading was 20 nm and 45 nm, respectively. Finally, the grading structures accompanied with further optimization of doped layers were integrated to achieve a cell efficiency of 8.59 %.

Microcrystalline silicon solar cells with passivated interfaces for high open-circuit voltage

2015 ◽  
Vol 212 (4) ◽  
pp. 840-845 ◽  
Author(s):  
Simon Hänni ◽  
Mathieu Boccard ◽  
Grégory Bugnon ◽  
Matthieu Despeisse ◽  
Jan-Willem Schüttauf ◽  
...  
Keyword(s):  
Solar Cells ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Silicon Solar Cells ◽  
Microcrystalline Silicon

Temperature Dependent Transport in Microcrystalline PIN Diodes

2000 ◽  
Vol 609 ◽  
Author(s):  
T. Brammer ◽  
H. Stiebig ◽  
A. Lambertz ◽  
W. Reetz ◽  
H. Wagner
Keyword(s):  
Solar Cells ◽  
Fill Factor ◽  
Extraction Efficiency ◽  
Chemical Vapor ◽  
Open Circuit ◽  
Microcrystalline Silicon ◽  
Temperature Dependent ◽  
Dependent Transport ◽  
Silane Concentration ◽  
Interface Effects

ABSTRACTThe optoelectronic behavior of diodes deposited by plasma enhanced chemical vapor deposition was investigated for a series of different silane concentrations in the gas phase. The purpose of this work was to correlate device characteristics with inherent properties of microcrystalline silicon by experiments and numerical simulations. Dark diode characteristics and, therefore, the open circuit voltage behavior of this series were dominated by the bulk properties of the i-layer (equilibrium carrier concentration) as shown by numerical modeling. Measurement of the solar cell output parameters as a function of the temperature showed that the fill factor of solar cells with small silane concentrations is dominated by the dark diode characteristics. This is in contrast to the temperature dependent fill factor of solar cells with large silane concentration which is limited by the extraction efficiency of the photogenerated carriers. Interface effects dominated the temperature dependent blue response. The gain in blue response increased with temperature and silane concentration by up to 200 % which revealed transport limiting material properties in the vicinity of the p/i-interface. This behavior was attributed to the nucleation region.

Polymer solar cells based on very narrow-bandgap polyplatinynes with photocurrents extended into the near-infrared region

2008 ◽  
pp. 5484 ◽  
Author(s):  
Xing-Zhu Wang ◽  
Wai-Yeung Wong ◽  
Kai-Yin Cheung ◽  
Man-Kin Fung ◽  
Aleksandra B. Djurišić ◽  
...  
Keyword(s):  
Solar Cells ◽  
Near Infrared ◽  
Polymer Solar Cells ◽  
Infrared Region ◽  
Narrow Bandgap ◽  
Near Infrared Region
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