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.

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.

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.

Deposition of P-Type Nanocrystalline Silicon Using High Pressure in a VHF-PECVD Single Chamber System

2011 ◽  
Vol 1321 ◽  
Author(s):  
Xiaodan Zhang ◽  
Guanghong Wang ◽  
Xinxia Zheng ◽  
Shengzhi Xu ◽  
Changchun Wei ◽  
...  
Keyword(s):  
High Pressure ◽  
Solar Cells ◽  
Solar Cell ◽  
Conversion Efficiency ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Nanocrystalline Silicon ◽  
Open Circuit ◽  
Single Chamber ◽  
P Type

ABSTRACTIn this article, we present a study of boron-doped hydrogenated nanocrystalline silicon (nc-Si: H) films by very high frequency-plasma enhanced chemical vapor deposition (VHF-PECVD) using high deposition pressure. Electrical, structural and optical properties of the films were investigated. Dark conductivity as high as 2.75S/cm of p-type nc-Si: H prepared at 2.5Torr pressure has been achieved at a deposition rate of 1.75Å/s for 25nm thin film. By controlling boron and phosphorus contamination, single junction nc-Si: H solar cells incorporated p-layers prepared under high pressure and low pressure, respectively, were deposited. It has been proven that nanocrystalline silicon solar cells with incorporation of p layer prepared at high pressure has resulted in enhanced open circuit voltage, short circuit current density and subsequently high conversion efficiency. Through the optimization of the bottom solar cell and application of ZnO/Al back reflector, 10.59% initial conversion efficiency of micromorph tandem solar cell (1.027cm2) with an open circuit voltage of 1.3864V, has been fabricated, where the bottom solar cell using a high pressure p layer was deposited in a single chamber.

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.

Optoelectronic Properties of Thin Amorphous and Micro-Crystalline p-Type Films Developed for Amorphous Silicon-Based Solar Cells

1996 ◽  
Vol 420 ◽  
Author(s):  
K. Winz ◽  
B. Rech ◽  
T. H. Eickhoff ◽  
C. Beneking ◽  
C. M. Fortmann ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Amorphous Silicon ◽  
Crystalline Silicon ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Glass Substrates ◽  
Cell Structures ◽  
Silicon Carbon ◽  
P Type

AbstractVIIF-PECVD at 110 MI-z was used to deposit micro-crystalline p-layers on glass substrates for detailed analysis and onto ZnO coated substrates for incorporation into p-i-n solar cell structures. Solar cell and film analysis confirmed that the films incorporated into the solar cells contained significant crystalline silicon volume fractions despite being only 30 nm thick. The p-i-n solar cells employing a micro-crystalline silicon p-layer deposited on ZnO coated substrates had series resistances, fill factors and Voc similar to those of the reference solar cells deposited onto SnO2 coated substrates and having optimized amorphous silicon-carbon p-layers. The short circuit current of the micro-crystalline p-layer case was 10 percent lower than that of the reference cell indicating that further optimization is required.

scholarly journals Improving Efficiency of Evaporated Cu2ZnSnS4Thin Film Solar Cells by a Thin Ag Intermediate Layer between Absorber and Back Contact

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Hongtao Cui ◽  
Chang-Yeh Lee ◽  
Wei Li ◽  
Xiaolei Liu ◽  
Xiaoming Wen ◽  
...  
Keyword(s):  
Solar Cells ◽  
Carrier Transport ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Depletion Region ◽  
Short Circuit Current Density ◽  
Open Circuit ◽  
Back Contact ◽  
Secondary Phases ◽  
P Type

A 20 nm Ag coating on Mo back contact was adopted to improve the back contact of evaporated Cu2ZnSnS4(CZTS) solar cells. The Ag layer helped reduce the thickness of MoS2which improves fill factor (FF) significantly; additionally, it reduced secondary phases ZnS and SnS2−x, which may help carrier transport; it was also involved in the doping of the absorber layer, which compensated the intrinsic p-type doping and therefore drags down the doping level. The doping involvement may enlarge the depletion region and improve lifetime of the absorber, which led to enhancing open circuit voltage (VOC), short circuit current density (JSC), and efficiency significantly. However, it degrades the crystallinity of the material slightly.

scholarly journals Optimization of Recombination Layer in the Tunnel Junction of Amorphous Silicon Thin-Film Tandem Solar Cells

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Yang-Shin Lin ◽  
Shui-Yang Lien ◽  
Chao-Chun Wang ◽  
Chia-Hsun Hsu ◽  
Chih-Hsiang Yang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Amorphous Silicon ◽  
High Efficiency ◽  
Short Circuit ◽  
Open Circuit ◽  
Maximum Efficiency ◽  
Manufacturing Cost ◽  
Silicon Thin Film ◽  
Tandem Solar Cells ◽  
Tandem Cell

The amorphous silicon/amorphous silicon (a-Si/a-Si) tandem solar cells have attracted much attention in recent years, due to the high efficiency and low manufacturing cost compared to the single-junction a-Si solar cells. In this paper, the tandem cells are fabricated by high-frequency plasma-enhanced chemical vapor deposition (HF-PECVD) at 27.1 MHz. The effects of the recombination layer and the i-layer thickness matching on the cell performance have been investigated. The results show that the tandem cell with a p+recombination layer and i2/i1thickness ratio of 6 exhibits a maximum efficiency of 9.0% with the open-circuit voltage (Voc) of 1.59 V, short-circuit current density (Jsc) of 7.96 mA/cm2, and a fill factor (FF) of 0.70. After light-soaking test, our a-Si/a-Si tandem cell with p+recombination layer shows the excellent stability and the stabilized efficiency of 8.7%.

Synthesis of TiO2 Nanopowders and their Applications in Dye-Sensitized Solar Cell

2010 ◽  
Vol 663-665 ◽  
pp. 848-851
Author(s):  
Jian Sun ◽  
Yan Xiang Wang ◽  
Min Xu ◽  
Ting Li Ma ◽  
Xue Yun Fan
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
High Efficiency ◽  
Low Cost ◽  
Short Circuit ◽  
Sol Gel ◽  
Dye Sensitized Solar Cells ◽  
Open Circuit ◽  
Dye Sensitized ◽  
Tio2 Nanopowders

Dye-sensitized solar cells (DSSC) are currently attracting widespread interest for the conversion of sunlight into electricity because of their low cost and high efficiency. In these cells, photo-anode is one of the key components for high power conversion efficiencies. In this paper, TiO2 nanopowders were prepared by the non-hydrolytic sol-gel method using TiCl4 as precursor, absolute ethanol and isopropanol as oxygen donor. Several different TiO2 nanopowders were used to fabricate TiO2 solar cells, and properties of TiO2 solar cells were characterized. The solar cell prepared with grainsize 50~80nm TiO2 nanopowders generated a short-circuit photocurrent of 13.17 mA/cm2, an open-circuit photovoltage of 789 mV, a fill factor of 69.8% and the efficiency of 7.25% under the light intensity of 100 mW/cm2.

scholarly journals Anti-LID Process with a Remote Direct Heating Method Using a Half-Bridge Resonance Circuit for a PERC Solar Cell Module

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 110
Author(s):  
Soo Min Kim ◽  
Sanghoon Jung ◽  
Yoonkap Kim ◽  
Junhee Kim
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
High Efficiency ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Heating Method ◽  
High Efficiency Solar Cells ◽  
P Type ◽  
Cell Module ◽  
Solar Cell Module

As the importance of the levelized cost of electricity (LCOE) increases in the solar cell industry, the demand for high-efficiency solar cells is rapidly increasing. Typically, p-type passivated emitter rear contact (PERC) solar cells are the most commonly used in the industry, and their efficiency is approximately 22–23%. P-type solar cells are reported to exhibit a light-induced degradation (LID) phenomenon, in which their output constantly decreases during power generation under solar radiation, and the output significantly reduces as their reference efficiency increases. Ultra-high-efficiency solar cells, which are on high demand, have a considerable output reduction due to the LID phenomenon; hence, technologies to prevent the LID phenomenon are required. However, research on this phenomenon has not been conducted because there is no method to transfer heat to solar cells inside the encapsulant when the modules are produced. In this study, a regeneration state was formed by remotely heating solar cells without damaging the encapsulant of the solar cell module. This was accomplished by using a heating method based on an induction magnetic field. A half-bridge resonance circuit was used to apply the induction magnetic field, and the temperature of the solar cell was controlled by adjusting the magnitude of the current flowing through the coil. To determine whether only the solar cell was heated, the temperature distribution inside the module was analyzed using an IR camera. The minority carrier lifetime was examined by real-time observation of the open-circuit voltage pattern of the solar cell. Finally, the observed real-time open-circuit voltage data were used, and dynamic simulation of the regeneration process was applied to analyze the LID activation energy generated in the regeneration process of the solar cell module. In conclusion, research was conducted on applying the regeneration state to prevent the LID phenomenon in the solar-cell-module stage, and the LID activation energy of the solar cell module was extracted. Based on this, a nondestructive degradation prevention technology for the solar cell module was developed.

scholarly journals Simulation and characterization of planar high-efficiency back contact silicon solar cells

2021 ◽  
Vol 24 (3) ◽  
pp. 319-327
Author(s):  
A.V. Sachenko ◽  
◽  
V.P. Kostylyov ◽  
R.M. Korkishko ◽  
V.M. Vlasiuk ◽  
...  
Keyword(s):  
Solar Cells ◽  
High Efficiency ◽  
Short Circuit ◽  
Surface Recombination ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Back Contact ◽  
Planar Surfaces ◽  
High Efficiency Solar Cells

Short-circuit current, open-circuit voltage, and photoconversion efficiency of silicon high-efficiency solar cells with all back contact (BCSC) with planar surfaces have been calculated theoretically. In addition to the recombination channels usually considered in this kind of modeling, namely, radiative, Auger, Shockley–Read–Hall, and surface recombination, the model also takes into account the nonradiative trap-assisted exciton Auger recombination and recombination in the space charge region. It is ascertained that these two recombination mechanisms are essential in BCSCs in the maximum power operation regime. The model results are in good agreement with the experimental results from the literature.

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