Effects of Band Offsets on a-Sic:H/c-Si Heterojunction Solar Cell Performance

1998 ◽  
Vol 507 ◽  
Author(s):  
M. W. M. Van Cleef ◽  
F. A. Rubinelli ◽  
R. E. I. Schropp
Keyword(s):  
Solar Cells ◽  
Valence Band ◽  
Conduction Band ◽  
Fill Factor ◽  
Open Circuit ◽  
Tunnel Barrier ◽  
Solar Cell Performance ◽  
Band Offsets ◽  
Heterojunction Solar Cells ◽  
Simulation Results

ABSTRACTWe used the internal photoemission technique to determine the exact valence and conduction band offsets at the a-SiC:H/c-Si interface and investigated with numerical simulations their effects on the photocarrier collection in p+a-SiC:H/n c-Si heterojunction solar cells. The valence and conduction band offsets were found to be 0.60 eV and 0.55 eV, respectively. Simulation results show that a high valence band offset increases the open circuit voltage (higher built-in potential) but on the other hand can decrease the fill factor (by blocking the collection of photogenerated holes at the front contact). Interestingly, despite having a large barrier inside the valence band (ΔEv = 0.6 eV), our highly doped p+a-SiC:H/n c-Si heterojunction solar cells show no collection problems (FF= 0.73). Both IPE measurements and simulation results indicate that tunneling of holes through this barrier in the valence band can explain this effect. For thin highly doped (Eact = 0.33 eV) p+a-SiC:H layers, the tunnel barrier becomes very narrow (< 70 Å) and the tunneling probability is strongly enhanced.

Resistive Losses at c-Si/a-Si:H/ZnO Contacts for Heterojunction Solar Cells

2007 ◽  
Vol 989 ◽  
Author(s):  
Florian Einsele ◽  
Phillip Johannes Rostan ◽  
Uwe Rau
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Fill Factor ◽  
High Efficiency ◽  
Surface Recombination ◽  
Open Circuit ◽  
Surface Recombination Velocity ◽  
High Hydrogen ◽  
Solar Cell Performance ◽  
Heterojunction Solar Cells

AbstractWe study resistive losses at (p)c-Si/(p)Si:H/(n)ZnO heterojunction back contacts for high efficiency silicon solar cells. We find that a low tunnelling resistance for the (p)a-Si:H/(n)ZnO part of the junction requires deposition of Si:H with a high hydrogen dilution RH > 40 resulting in a highly doped μc-Si:H layer. Such a μc-Si:H layer if deposited directly on a Si wafer yields a surface recombination velocity of S  180 cm/s. Using the same layer as part of a (p)c-Si/(p)Si:H/(n)ZnO back contact in a solar cell results in an open circuit voltage Voc = 640 mV and a fill factor FF = 80 %. Insertion of an (i)a-Si-layer between the μc-Si:H and the wafer leads to a further decrease of S and, for the solar cells to an increase of VOC. However, if the thickness of this intrinsic layer exceeds a threshold of 3 nm, resistive losses lead to a degradation of the fill factor of the solar cells. These resistive losses result from a valence band offset δEV between a-Si:H and c-Si of about 600 meV. The fill factor losses overcompensate the VOC gain such that there is no benefit of the (i)a-Si:H interlayer for the overall solar cell performance when using an (i)a-Si:H/(p)uc-Si:H double layer.

Simulation of InAIN/Si Single-Heterojunction Solar Cells Using wxAMPS

2014 ◽  
Vol 665 ◽  
pp. 111-114 ◽  
Author(s):  
Ying Huang ◽  
Xiao Ming Shen ◽  
Xiao Feng Wei
Keyword(s):  
Solar Cells ◽  
Fill Factor ◽  
High Efficiency ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Indium Content ◽  
Open Circuit ◽  
Heterojunction Solar Cells ◽  
Si Solar Cells

In this paper, InAlN/Si single-heterojunction solar cells have been theoretically simulated based on wxAMPS software. The photovoltaic parameters, such as open circuit voltage, short circuit current, fill factor and conversion efficiency were investigated with changing the indium content and thickness of n-InAlN layer. Simulation results show that the optimum efficiency of InAlN/Si solar cells is 23.1% under AM 1.5G spectral illuminations, with the indium content and thickness of n-InAlN layer are 0.65 and 600nm, respectively. The simulation would contribute to design and fabricate high efficiency InAlN/Si solar cells in experiment.

scholarly journals Influence of Defect States and Thickness of Interface Layer On High Efficiency of c-Si/a-Si:H Heterojunction Solar Cells With Higher Bandgap a-Si:H(p) Layer By Simulation

2021 ◽  
Author(s):  
Venkanna Kanneboina
Keyword(s):  
Solar Cells ◽  
High Efficiency ◽  
Defect Density ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Interface Layer ◽  
Open Circuit ◽  
Defect States ◽  
Solar Cell Performance ◽  
Heterojunction Solar Cells

Abstract This paper presents the influence of defect states and thickness of interface layer on high efficiency of c-Si/a-Si:H heterojunction solar cells with higher bandgap emitter a-Si:H(p) layer by AFORSHET simulation tool. At first, the performance of Ag/ZnO/a-Si:H(p)/ a-Si:H(i)/ c-Si(n)/ a-Si:H(i)/ a-Si:H(n)/Ag heterojunction solar cells was studied by altering the thickness of a-Si:H(p) and a-Si:H(i) layers. The best values of open circuit voltage (Voc) (764.8 mV), short circuit current density (Jsc) (43.15 mA/cm2), fill factor (FF) (85.71) and efficiency(ɳ) (28.28%) were obtained at 3 nm of a-Si:H(p) and a-Si:H(i) layer. In the same structure, c-Si(n) interface was introduced in between c-Si(n) and a-Si:H(i) layer. It is found that the solar cell performance was not changed by varying defect density from 109-1014 cm-3 for thin (5 and 10 nm) interface layer and estimated values are 761.7 mV, 38.83 mA/cm2, 86.09%, 25.46% correspond to Voc, Jsc, FF, ɳ respectively. For very thick interface layer, defect density has shown huge impact on the device performance. At 1 µm, the Voc, FF and ɳ values have been changed from 760.2 to 653.2 mV, 85.9 to 80.76% and 22.94 to 18.47% for the defect density of 109 to 1014 cm-3 respectively.

scholarly journals Fabrication of Affordable and Sustainable Solar Cells Using NiO/TiO2 P-N Heterojunction

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Kingsley O. Ukoba ◽  
Freddie L. Inambao ◽  
Andrew C. Eloka-Eboka
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Fill Factor ◽  
Open Circuit Voltage ◽  
Spray Pyrolysis Technique ◽  
Low Cost ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Heterojunction Solar Cells

The need for affordable, clean, efficient, and sustainable solar cells informed this study. Metal oxide TiO2/NiO heterojunction solar cells were fabricated using the spray pyrolysis technique. The optoelectronic properties of the heterojunction were determined. The fabricated solar cells exhibit a short-circuit current of 16.8 mA, open-circuit voltage of 350 mV, fill factor of 0.39, and conversion efficiency of 2.30% under 100 mW/cm2 illumination. This study will help advance the course for the development of low-cost, environmentally friendly, and sustainable solar cell materials from metal oxides.

Effect of the Impurity Concentration of a-Si:H on the Properties of a-Si:H/c-S Heterojunction Solar Cells

2012 ◽  
Vol 485 ◽  
pp. 461-464
Author(s):  
Lan E Luo ◽  
Chun Liang Zhong
Keyword(s):  
Solar Cells ◽  
Doping Level ◽  
Impurity Concentration ◽  
Fill Factor ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Depletion Region ◽  
Open Circuit ◽  
High Doping Level ◽  
Heterojunction Solar Cells

Effect of the impurity concentration of a-Si:H, ND2, on the properties of a-Si:H/c-S heterojunction solar cells is studied by a set of AMPS simulations. The results show that the short-circuit current almost not depends on ND2. At a low doping level, the electric field redistributes in the c-Si depletion region and the barrier at the heterojunction interface hinders the collection of photogenerated holes. It results in an enhanced recombination inside the c-Si depletion region and the S-Shaped J-V characteristics. As a sequence, the open-circuit voltage VOC and the fill factor FF decreases with ND2 decreasing. However, at a high doping level, VOC and FF is independent on ND2 as the diffusion potential is mainly accommodated in the c-Si. So the efficiency increases with ND2 increasing at a low doping level, and then is independent on ND2 at a high doping level. Therefore, to improve the properties of a-Si:H/c-Si heterojunction solar cells, the a-Si:H layer should be highly doped.

scholarly journals Role of Vanadium Pentoxide Hole-Extracting Nanolayer in Rubrene/C70-Based Small Molecule Organic Solar Cells

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Zhen Zhan ◽  
Jing Cao ◽  
Weiguang Xie ◽  
Lintao Hou ◽  
Qin Ye ◽  
...  
Keyword(s):  
Solar Cells ◽  
Vanadium Pentoxide ◽  
Organic Solar Cells ◽  
Fill Factor ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Hole Transport ◽  
Heterojunction Solar Cells

Vanadium pentoxideV2O5was inserted between the donor layer and the anode as a hole-extracting nanolayer. Compared with devices without a hole-extracting layer, short-circuit current density (JSC), open-circuit voltage (VOC), fill factor (FF), and power conversion efficiency (PCE) of rubrene/C70-based heterojunction solar cells with 3 nm V2O5nanolayer are enhanced by 99%, 73%, 20%, and 310%, respectively. We found that V2O5interlayer can effectively suppress the contact resistance and increase the hole transport capability. The dependence of the device performance on V2O5layer thickness as well as fill factor on exciton dissociation and charge transport was also investigated in detail.

Microcrystalline (Si,Ge):H Solar Cells

2003 ◽  
Vol 762 ◽  
Author(s):  
Jianhua Zhu ◽  
Vikram L. Dalal
Keyword(s):  
Solar Cells ◽  
Buffer Layer ◽  
Quantum Efficiency ◽  
Fill Factor ◽  
Open Circuit Voltage ◽  
Defect Density ◽  
Cell Structure ◽  
Open Circuit ◽  
Base Layer ◽  
Ecr Plasma

AbstractWe report on the growth and properties of microcrystalline Si:H and (Si,Ge):H solar cells on stainless steel substrates. The solar cells were grown using a remote, low pressure ECR plasma system. In order to crystallize (Si,Ge), much higher hydrogen dilution (∼40:1) had to be used compared to the case for mc-Si:H, where a dilution of 10:1 was adequate for crystallization. The solar cell structure was of the p+nn+ type, with light entering the p+ layer. It was found that it was advantageous to use a thin a-Si:H buffer layer at the back of the cells in order to reduce shunt density and improve the performance of the cells. A graded gap buffer layer was used at the p+n interface so as to improve the open-circuit voltage and fill factor. The open circuit voltage and fill factor decreased as the Ge content increased. Quantum efficiency measurements indicated that the device was indeed microcrystalline and followed the absorption characteristics of crystalline ( Si,Ge). As the Ge content increased, quantum efficiency in the infrared increased. X-ray measurements of films indicated grain sizes of ∼ 10nm. EDAX measurements were used to measure the Ge content in the films and devices. Capacitance measurements at low frequencies ( ~100 Hz and 1 kHz) indicated that the base layer was indeed behaving as a crystalline material, with classical C(V) curves. The defect density varied between 1x1016 to 2x1017/cm3, with higher defects indicated as the Ge concentration increased.

Kinetics of Light-Induced Effects in Mixed-Phase Hydrogenated Silicon Solar Cells

2003 ◽  
Vol 762 ◽  
Author(s):  
Guozhen Yuea ◽  
Baojie Yan ◽  
Jeffrey Yang ◽  
Kenneth Lord ◽  
Subhendu Guha
Keyword(s):  
Solar Cells ◽  
Fill Factor ◽  
Equivalent Circuit Model ◽  
Open Circuit ◽  
Mixed Phase ◽  
Silicon Solar Cells ◽  
Initial Increase ◽  
Soaking Time ◽  
Hydrogenated Silicon ◽  
Kinetics Of

AbstractWe have observed a significant light-induced increase in the open-circuit voltage (Voc) of mixed-phase hydrogenated silicon solar cells. In this study, we investigate the kinetics of the light-induced effects. The results show that the cells with different initial Voc have different kinetic behavior. For the cells with a low initial Voc (less than 0.8 V), the increase in Voc is slow and does not saturate for light-soaking time of up to 16 hours. For the cells with medium initial Voc (0.8 ∼ 0.95 V), the Voc increases rapidly and then saturates. Cells with high initial Voc (0.95 ∼ 0.98 V) show an initial increase in Voc, followed bya Voc decrease. All light-soaked cells exhibit a degradation in fill factor. The temperature dependence of the kinetics shows that light soaking at high temperatures causes Voc increase to saturate faster than at low temperatures. The observed results can be explained by our recently proposed two-diode equivalent-circuit model for mixed-phase solar cells.

Non-geminate Recombination Limits Fill Factor in Polymer:ITIC Bulk Heterojunction Solar Cells

2019 ◽  
Author(s):  
Jafar Khan ◽  
Yuliar Firdaus ◽  
Federico Cruciani ◽  
Shengjian Liu ◽  
Denis Andrienko ◽  
...  
Keyword(s):  
Solar Cells ◽  
Fill Factor ◽  
Bulk Heterojunction ◽  
Geminate Recombination ◽  
Heterojunction Solar Cells ◽  
Bulk Heterojunction Solar Cells
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