scholarly journals Numerical Simulation Analysis of Ag Crystallite Effects on Interface of Front Metal and Silicon in the PERC Solar Cell

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 592
Author(s):  
Myeong Sang Jeong ◽  
Yonghwan Lee ◽  
Ka-Hyun Kim ◽  
Sungjin Choi ◽  
Min Gu Kang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
High Efficiency ◽  
Open Circuit Voltage ◽  
Surface Recombination ◽  
Open Circuit ◽  
Surface Recombination Velocity ◽  
Metal Interface ◽  
Ag Crystallites ◽  
Recombination Velocity

In the fabrication of crystalline silicon solar cells, the contact properties between the front metal electrode and silicon are one of the most important parameters for achieving high-efficiency, as it is an integral element in the formation of solar cell electrodes. This entails an increase in the surface recombination velocity and a drop in the open-circuit voltage of the solar cell; hence, controlling the recombination velocity at the metal-silicon interface becomes a critical factor in the process. In this study, the distribution of Ag crystallites formed on the silicon-metal interface, the surface recombination velocity in the silicon-metal interface and the resulting changes in the performance of the Passivated Emitter and Rear Contact (PERC) solar cells were analyzed by controlling the firing temperature. The Ag crystallite distribution gradually increased corresponding to a firing temperature increase from 850 ∘C to 950 ∘C. The surface recombination velocity at the silicon-metal interface increased from 353 to 599 cm/s and the open-circuit voltage of the PERC solar cell decreased from 659.7 to 647 mV. Technology Computer-Aided Design (TCAD) simulation was used for detailed analysis on the effect of the surface recombination velocity at the silicon-metal interface on the PERC solar cell performance. Simulations showed that the increase in the distribution of Ag crystallites and surface recombination velocity at the silicon-metal interface played an important role in the decrease of open-circuit voltage of the PERC solar cell at temperatures of 850–900 ∘C, whereas the damage caused by the emitter over fire was determined as the main cause of the voltage drop at 950 ∘C. These results are expected to serve as a steppingstone for further research on improvement in the silicon-metal interface properties of silicon-based solar cells and investigation on high-efficiency solar cells.

High-Efficiency HIT Solar Cells for Excellent Power Generating Properties

2008 ◽  
Vol 1123 ◽  
Author(s):  
Toshihiro Kinoshita ◽  
Daisuke Ide ◽  
Yasufumi Tsunomura ◽  
Shigeharu Taira ◽  
Toshiaki Baba ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Conversion Efficiency ◽  
Production Cost ◽  
High Efficiency ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Open Circuit ◽  
Surface Recombination Velocity ◽  
Dominant Factor

AbstractIn order to achieve the widespread use of HIT (Hetero-junction with I etero-Intrinsic T ntrinsic Thin-layer) solar cells, it is important to reduce the power generating cost. There are three main approaches for reducing this cost: raising the conversion efficiency of the HIT cell, using a thinner wafer to reduce the wafer cost, and raising the open circuit voltage to obtain a better temperature coefficient. With the first approach, we have achieved the highest conversion efficiency values of 22.3%, confirmed by AIST, in a HIT solar cell. This cell has an open circuit voltage of 0.725 V, a short circuit current density of 38.9 mA/cm2 and a fill factor of 0.791, with a cell size of 100.5 cm2. The second approach is to use thinner Si wafers. The shortage of Si feedstock and the strong requirement of a lower sales price make it necessary for solar cell manufacturers to reduce their production cost. The wafer cost is an especially dominant factor in the production cost. In order to provide low-priced, high-quality solar cells, we are trying to use thinner wafers. We obtained a conversion efficiency of 21.4% (measured by Sanyo) for a HIT solar cell with a thickness of 85μm. Even better, there was absolutely no sagging in our HIT solar cell because of its symmetrical structure. The third approach is to raise the open circuit voltage. We obtained a remarkably higher Voc of 0.739 V with the thinner cell mentioned above because of its low surface recombination velocity. The high Voc results in good temperature properties, which allow it to generate a large amount of electricity at high temperatures.

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.

17.8%-efficient Amorphous Silicon Heterojunction Solar Cells on p-type Silicon Wafers

2006 ◽  
Vol 910 ◽  
Author(s):  
Qi Wang ◽  
Matt P. Page ◽  
Eugene Iwancizko ◽  
Yueqin Xu ◽  
Yanfa Yan ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
High Efficiency ◽  
Short Circuit ◽  
Open Circuit ◽  
Layer Growth ◽  
Surface Recombination Velocity ◽  
Back Contact ◽  
P Type

AbstractWe have achieved an independently-confirmed 17.8% conversion efficiency in a 1-cm2, p-type, float-zone silicon (FZ-Si) based heterojunction solar cell. Both the front emitter and back contact are hydrogenated amorphous silicon (a-Si:H) deposited by hot-wire chemical vapor deposition (HWCVD). This is the highest reported efficiency for a HWCVD silicon heterojunction (SHJ) solar cell. Two main improvements lead to our most recent increases in efficiency: 1) the use of textured Si wafers, and 2) the application of a-Si:H heterojunctions on both sides of the cell. Despite the use of textured c-Si to increase the short-circuit current, we were able to maintain the same 0.65 V open-circuit voltage as on flat c-Si. This is achieved by coating a-Si:H conformally on the c-Si surfaces, including covering the tips of the anisotropically-etched pyramids. A brief atomic H treatment before emitter deposition is not necessary on the textured wafers, though it was helpful in the flat wafers. It is essential to high efficiency SHJ solar cells that the emitter grows abruptly as amorphous silicon, instead of as microcrystalline or epitaxial Si. The contact on each side of the cell comprises a thin (< 5 nm) low substrate temperature (~100°C) intrinsic a-Si:H layer, followed by a doped layer. Our intrinsic layers are deposited at 0.3-1.2 nm/s. The doped emitter and back-contact layers were deposited at a higher temperature (>200°C) and grown from PH3/SiH4/H2 and B2H6/SiH4/H2 doping gas mixtures, respectively. This combination of low (intrinsic) and high (doped layer) growth temperatures was optimized by lifetime and surface recombination velocity measurements. Our rapid efficiency advance suggests that HWCVD may have advantages over plasma-enhanced (PE) CVD in fabrication of high-efficiency heterojunction c-Si cells; there is no need for process optimization to avoid plasma damage to the delicate, high-quality, Si wafers.

The Study of Optical and Electrical Properties of a-SiC:H for Multi-junction Si Thin Film Solar Cell

2010 ◽  
Vol 1245 ◽  
Author(s):  
Jenny H. Shim ◽  
W.K. Yoon ◽  
S.T. Hwang ◽  
S.W. Ahn ◽  
H.M. Lee
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
High Efficiency ◽  
Open Circuit Voltage ◽  
Defect Density ◽  
Wide Bandgap ◽  
Open Circuit ◽  
Deposition Condition ◽  
Wide Bandgap Material ◽  
Pressure Regime

AbstractStudies have shown that wide bandgap material is required for high efficiency multi-junction solar cell applications. Here, we address proper deposition condition for high quality a-SiC:H films. In high power high pressure regime, we observed that the defect density get much lowered to the similar defect level of a-Si:H film with high H2 dilution. Single junction solar cells fabricated with the optimized condition show high open circuit voltage and low LID effect. The degradation after the LID test was only 13 % reduction of the efficiency indicating that a-SiC:H could be promising material for multi-junction solar cells.

A high efficiency solution processed polymer inverted triple-junction solar cell exhibiting a power conversion efficiency of 11.83%

2015 ◽  
Vol 8 (1) ◽  
pp. 303-316 ◽  
Author(s):  
Abd. Rashid bin Mohd Yusoff ◽  
Dongcheon Kim ◽  
Hyeong Pil Kim ◽  
Fabio Kurt Shneider ◽  
Wilson Jose da Silva ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Triple Junction ◽  
High Efficiency ◽  
Open Circuit Voltage ◽  
Power Conversion ◽  
Open Circuit ◽  
Tandem Solar Cells

We propose that 1 + 1 + 1 triple-junction solar cells can provide an increased efficiency, as well as a higher open circuit voltage, compared to tandem solar cells.

High Open-Circuit Voltage in Silicon Heterojunction Solar Cells

2007 ◽  
Vol 989 ◽  
Author(s):  
Qi Wang ◽  
Matt R. Page ◽  
Eugene Iwancizko ◽  
Yueqin Xu ◽  
Lorenzo Roybal ◽  
...  
Keyword(s):  
Amorphous Silicon ◽  
Open Circuit Voltage ◽  
Surface Recombination ◽  
Open Circuit ◽  
Surface Recombination Velocity ◽  
Back Surface ◽  
Float Zone ◽  
Double Heterojunction ◽  
Type C ◽  
Recombination Velocity

AbstractHigh open-circuit voltage (Voc) silicon heterojunction (SHJ) solar cells are fabricated in double-heterojunction a-Si:H/c-Si/a-Si:H structures using low temperature (<225°C) hydrogenated amorphous silicon (a-Si:H) contacts deposited by hot-wire chemical vapor deposition (HWCVD). On p-type c-Si float-zone wafers, we used an amorphous n/i contact to the top surface and an i/p contact to the back surface to obtain a Voc of 667 mV in a 1 cm2 cell with an efficiency of 18.2%. This is the best reported p-type SHJ voltage. In our labs, it improves over the 652 mV cell obtained with a front amorphous n/i heterojunction emitter and a high-temperature alloyed Al back-surface-field contact. On n-type c-Si float-zone wafers, we used an a Si:H (p/i) front emitter and an a-Si:H (i/n) back contact to achieve a Voc of 691 mV on 1 cm2 cell. Though not as high as the 730 mV reported by Sanyo on n-wafers, this is the highest reported Voc for SHJ c-Si cells processed by the HWCVD technique. We found that effective c-Si surface cleaning and a double-heterojunction are keys to obtaining high Voc. Transmission electron microscopy reveals that high Voc cells require an abrupt interface from c-Si to a-Si:H. If the transition from the base wafer to the a-Si:H incorporates either microcrystalline or epitaxial Si at c Si interface, a low Voc will result. Lifetime measurement shows that the back-surface-recombination velocity (BSRV) can be reduced to ~15 cm/s through a-Si:H passivation. Amorphous silicon heterojunction layers on crystalline wafers thus combine low-surface recombination velocity with excellent carrier extraction.

High efficiency and high open-circuit voltage quadruple-junction silicon thin film solar cells for future electronic applications

2017 ◽  
Vol 10 (5) ◽  
pp. 1134-1141 ◽  
Author(s):  
Bofei Liu ◽  
Lisha Bai ◽  
Tiantian Li ◽  
Changchun Wei ◽  
Baozhang Li ◽  
...  
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Thin Film Solar Cell ◽  
High Efficiency ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Thin Film Solar Cells ◽  
Silicon Thin Film ◽  
Silicon Based

A highly efficient quadruple-junction silicon based thin-film solar cell with a remarkably high open-circuit voltage was demonstrated to inspire functional photoelectrical devices for environmental applications.

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