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 ◽  
...  

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.

2008 ◽  
Vol 1123 ◽  
Author(s):  
Toshihiro Kinoshita ◽  
Daisuke Ide ◽  
Yasufumi Tsunomura ◽  
Shigeharu Taira ◽  
Toshiaki Baba ◽  
...  

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.


2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Hwen-Fen Hong ◽  
Tsung-Shiew Huang ◽  
Wu-Yih Uen ◽  
Yen-Yeh Chen

We performed accelerated tests on sealed and nonsealed InGaP/InGaAs/Ge triple-junction (TJ) solar cells in a complex high temperature and high humidity environment and investigated the electrical properties over time. The degradation of energy conversion efficiency in nonsealed cells was found to be more serious than that in sealed cells. The short-circuit current (ISC), open-circuit voltage (VOC), and fill factor (FF) of sealed cells changed very slightly, though the conversion efficiency decreased 3.6% over 500 h of exposure. This decrease of conversion efficiency was suggested to be due to the deterioration of silicone encapsulant. TheISC,VOC, and FF of nonsealed cells decreased with increasing exposure time. By EL and SEM analysis, the root causes of degradation can be attributed to the damage and cracks near the edge of cells induced by the moisture ingress. It resulted in shunt paths that lead to a deterioration of the conversion efficiency of solar cell by increasing the leakage current, as well as decreasing open-circuit voltage and fill factor of nonsealed solar cells.


2006 ◽  
Vol 910 ◽  
Author(s):  
Qi Wang ◽  
Matt P. Page ◽  
Eugene Iwancizko ◽  
Yueqin Xu ◽  
Yanfa Yan ◽  
...  

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.


2021 ◽  
Vol 34 (1) ◽  
pp. 01-08
Author(s):  
B GopalKrishna ◽  
Sanjay Tiwari

Perovskite solar cells are emerging photovoltaic devices with PCE of above 25%. Perovskite are suitable light absorber materials in solar cells with excellent properties like appropriate band gap energy, long carrier lifetime and diffusion length, and high extinction coefficient. Simulation study is an important technique to understand working mechanisms of perovskites solar cells. The study would help develop efficient, stable PSCs experimentally. In this study, modeling of perovskite solar cell was carried out through Setfos software. The optimization of different parameters of layer structure of solar cell would help to achieve maximum light absorption in the perovskite layer of solar cell. Simulation study is based drift-diffusion model to study the different parameters of perovskite solar cell. Hysteresis is one of the factors in the perovskite solar cell which may influence the device performance. The measurement of abnormal hysteresis can be done by current-voltage curve during backward scan during simulation study. In backward scan, the measurement starts from biasing voltage higher than open circuit voltage and sweep to voltage below zero. The numerical simulation used to study the various parameters like open circuit voltage, short circuit current, fill factor, power conversion efficiency and hysteresis. The simulation results would help to understand the photophysics of solar cell physics which would help to fabricate highly efficient and stable perovskite solar cells experimentally.


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 ◽  
...  

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.


2011 ◽  
Vol 347-353 ◽  
pp. 3666-3669
Author(s):  
Ming Biao Li ◽  
Li Bin Shi

The AMPS-ID program is used to investigate optical and electrical properties of the solar cell of a-SiC:H/a-Si1-xGex:H/a-Si:H thin films. The short circuit current density, open circuit voltage, fill factor and conversion efficiency of the solar cell are investigated. For x=0.1, the conversion efficiency of the solar cell achieve maximum 9.19 % at the a-Si1-xGex:H thickness of 340 nm.


Author(s):  
Omar Ghanim Ghazal ◽  
Ahmed Waleed Kasim ◽  
Nabeel Zuhair Tawfeeq

Cadmium telluride (CdTe)/cadmium sulfide (CdS) solar cell is a promising candidate for photovoltaic (PV) energy production, as fabrication costs are compared by silicon wafers. We include an analysis of CdTe/CdS solar cells while optimizing structural parameters. Solar cell capacitance simulator (SCAPS)-1D 3.3 software is used to analyze and develop energy-efficient. The impact of operating thermal efficiency on solar cells is highlighted in this article to explore the temperature dependence. PV parameters were calculated in the different absorber, buffer, and window layer thicknesses (CdTe, CdS, and SnO2). The effect of the thicknesses of the layers, and the fundamental characteristics of open-circuit voltage, fill factor, short circuit current, and solar energy conversion efficiency were studied. The results showed the thickness of the absorber and buffer layers could be optimized. The temperature had a major impact on the CdTe/CdS solar cells as well. The optimized solar cell has an efficiency performance of &gt;14% when exposed to the AM1.5 G spectrum. CdTe 3000 nm, CdS 50 nm, SnO2 500 nm, and (at) T 300k were the I-V characteristics gave the best conversion open circuit voltage (Voc)=0.8317 volts, short circuit current density (Jsc)=23.15 mA/cm2, fill factor (FF)%=77.48, and efficiency (η)%=14.73. The results can be used to provide important guidance for future work on multi-junction solar cell design.


Author(s):  
Limin Shao ◽  
Shuli Yang

A large area of sunlight onto solar cells is gathered by concentrating system for spacial concentrating solar array, which reduces the amount of solar cells by increasing light intensity onto the solar cells of the unit area. Under concentrating conditions, the short-circuit current, open-circuit voltage, fill factor, efficiency, operating temperature and strong thermal-electrical coupling characteristics of concentrating solar cells are different from the conventional solar cells because of the high intensity and high operating temperature. The concentrating module design, solar cell selection, and design of solar cell heat-dissipation have been carried out. The thermal-electric coupling model of special concentrating photovoltaic system has been established. The relationships among concentrated ratio, substrate-thickness, thermal conductivity of substrate-material and solar cell’s temperature, density of short-circuit current, open-circuit voltage, maximum output power have been analyzed, which provide a view to a reasonabl0e match and selection of multi-parameters in engineering design. Results show that the concentrated ratio has an overall effect on the open-circuit voltage, short-circuit current, efficiency and operating temperature of the solar cell. There is a strong coupling relationship among the parameters, and the positive and negative impacts caused by the concentrating characteristics should be weighed in the engineering design. The short-circuit current density of concentrating solar cells is proportional to the concentrated ratio. Under the lower concentrated ratio circumstance, fill factor and efficiency is not substantially affected by the concentrated ratio. The maximum output power and open-circuit voltage increase with the increase of concentrated ratio. Temperature of concentrating solar cells has an adverse effect on the open-circuit voltage, efficiency and output power, which needs high efficient radiator measures to be taken. The operating temperature of solar cells could be decreased significantly by the high thermal conductivity of the substrate-material. The concentrated ratio between 9~15 is recommended for spacial solar array, which not only embodies the advantage of concentrator like improving the cell-efficiency and decreasing the cost, but also doesn’t exact the deploying precision of concentrating system.


1981 ◽  
Vol 59 (11) ◽  
pp. 1682-1685 ◽  
Author(s):  
F. El Guibaly ◽  
K. Colbow

An improved model for the semiconductor–electrolyte solar cell is discussed. Charge transfer kinetics, surface recombination, recombination in the quasi neutral region and in the depletion region, as well as the series and shunt resistance of the cell are included in our model. It is shown that the surface transfer velocity of minority carriers across the semiconductor–electrolyte interface affects primarily the open circuit voltage, the fill factor and power conversion efficiency, and only to a lesser degree the short circuit current.As is the case with nonelectrolytic solid state solar cells, the series resistance of the electrochemical cell reduces the fill factor and the conversion efficiency, while the shunt resistance reduces the open circuit voltage of the cell in addition to reducing the fill factor and the power conversion efficiency.


2012 ◽  
Vol 1426 ◽  
pp. 161-166
Author(s):  
Daiji Kanematsu ◽  
Mitsuhiro Matsumoto ◽  
Shigeo Yata ◽  
Yoichiro Aya ◽  
Akira Terakawa ◽  
...  

ABSTRACTWe correlated the texture morphology and the solar cell properties by measuring the distribution in the texture morphology. As a result, the short-circuit current ISC was approximated across various types of substrates by the standard texture height. Furthermore, we investigated the texture morphology from the point of view of the electrical effects. With regard to this point, the open-circuit voltage VOC was correlated to the steepest texture angle. Therefore, we consider that the both of the ISC and the VOC can be improved by controlling the distribution in the texture morphology.


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