Light soak stress of bare cdscds cdte cdte cells vs. Semitransparent ultrathin cdte solar cells and durability. A study has been made to improve the efficiency of. Presented at the 2006 ieee 4th world conference on photovoltaic energy conversion wcpec4 held may 712, 2006 in waikoloa, hawaii. Characterization of cadmium zinc telluride solar cells. Cdte thinfilm solar cells can be manufactured quickly and inexpensively, providing a lowercost alternative to conventional siliconbased technologies. Cdte thickness a cc b d normalizedcell performanceparameters of four differentcdte thickness solar cells.
The iiiv semiconductor compound, cdte, has suitable electrical and optical properties as photovoltaic and highenergy radiation sensor material. Simulation of the efficiency of cdscdte tandem multi. Exploring back contact technology to increase cdscdte solar. The efficiency of cdte solar cells has reached just more than 15 percent, and cigs solar cells have reached 20 percent efficiency.
The cell was calibrated by the national renewable energy laboratorys. An overview of solar cell technology mike mcgehee materials science and engineering global climate and energy projectglobal climate and energy project center for advanced molecular photovoltaics precourt institute stanford university konarka nanosolar john benner provided the slides with the nrel logo. Cadmium telluride was originally considered for thin film solar cells because of its optimum band gap, high optical absorption coefficient and ability to be doped. Cadmium telluride cdte has long been recognized as a strong candidate for thin film solar cell applications. Cigs solar cell on a flexible plastic backing and rigid cdte panels mounted on a supporting structure. In amorphous silicon solar cells, lightinduced degradation has a recoverable and a nonrecoverable component too, and the details of the.
Study of efficiencies cdtecds photovoltaic solar cell. Cadmium telluride cdte solar cells have quietly established themselves as a mass market pv technology. The melting point of cdte is 1041 oc, and evaporation occurs at 1050 oc in open air and at about 900 c under nonoxidizing conditions. The amount of cd in cdte solar cells is very small, and could be reduced even further as the cells become thinner. It is mainly used as the semiconducting material in cadmium telluride photovoltaics and an infrared optical window. The layers succes sion and thicknesses are the one used in the present work.
Global solar cell market size was estimated at 182. We have grown solar cells on 1 mm thick glass but they can also be grown on very thin 50100 m cover glasses while a low cost encapsulation or lamination can be applied to protect the back of the modules. Design of a thin film cdte solar cell summary cadmium. High efficiency cdte and cigs thin film solar cells nrel.
Solar cells, covering single crystal, polycrystalline and amorphous materials utilising. Buffer layers are commonly used in the optimization of thinfilm solar cells. Pv array made of cadmium telluride cdte solar panels type of solar power cell cadmium telluride cdte photovoltaics describes a photovoltaic pv technology that is based on the use of cadmium telluride in a thin semiconductor layer designed to absorb and convert sunlight into electricity. Leaching of cadmium and tellurium from cadmium telluride. If all of it was used to make solar cells, we could generate 0. Cdte solar panels are now at parity with polycrystalline silicon for performance and cost. Life cycle impact analysis of cadmium in cdte pv production pdf. The solar cell current source generates a light current iph. Construct a band diagram of the cdscdte solar cell. Cdte solar cells have the potential to undercut the costs of electricity generated by other technologies, if the opencircuit voltage can be increased beyond 1 v without significant decreases in. Concentrator solar cells expense of multijunction cell.
The record efficiency for a laboratory cdte solar cell is 22. The study is carried out by simulation with scaps solar cell capacitance simulator whose mathematical model is based on solving the equations of poisson and continuity of electrons and holes. In addition to affecting the opencircuit voltage of a cell, it is commonly reported that buffer layers affect stressinduced degradation and transient phenomena in cdte and cuinse 2based solar cells. For cuinse 2and cdte based solar cells, multilayer transparent conductors tcos, e. Currently, first solar has announced a new world record this year for cdte pv solar cell efficiency of 17. Fcoated glass substrates with a lowtemperature cdte photovoltaic solar cells has been regaining momentum in recent years, due to commercial advances made with regard to cdte technology. Polycrystalline cdscdte solar cells al compaan distinguished university professor of physics, emeritus lecture for hebenellingson solar cells class mhmarch 15 201215, 2012 1. Cadmium telluride cdte institute of energy conversion. Pv solar cells based on cdte represent the largest segment of commercial thinfilm module production worldwide. A thinfilm solar cell is a second generation solar cell that is made by depositing one or more thin layers, or thin film tf of photovoltaic material on a substrate, such as glass, plastic or metal. The role of back buffer layers and absorber properties for. The leading thinfilm technology, cadmium telluride cdte, had a module production of 1. Optimum cell performance is usually found when the tco layer in contact with the cds is very resistive or almost insulating. There are health concerns with the use of cadmium in thinfilm solar cells.
Solar photovoltaic pv cells san jose state university. Pdf cdte solar cells with opencircuit voltage breaking. Rising penetration of renewable energy sources owing to environmental benefits coupled with increasing electricity demand is expected to propel market growth. Pdf simulation of cadmium telluride solar cells structure. A solar cell is an electronic device which directly converts sunlight into electricity. It is usually sandwiched with cadmium sulfide to form a pn junction solar pv cell. Durose 1 1stephenson institute for renewable energy and department of physics, school of physical sciences, chadwick building, university of. Due to their efficiency and relatively low manufacturing energy requirements, cdte solar cells had the shortest energy payback time among commercially relevant pv technologies. Pv solar cells based on cdte represent the largest segment of commercial thinfilm. A range of the deposition parameters is included in table 1. This is an important aspect to increase the specific power of cdte cds solar modules. Cadmium telluride cdte is a stable crystalline compound formed from cadmium and tellurium. Solar cells of 79% efficiency were developed on sno x. A big step forward in cost reduction is expected through the growth of solar cells.
This process requires firstly, a material in which the absorption of light raises an electron to a higher energy state. Cdte solar panel manufacturers companies involved in cdte solar panel production, a key thinfilm panel technology. Cdte solar cell has been stagnant for the last few years. Czt is deposited by cosublimation of cdte and znte. Cdte solar cells with opencircuit voltage breaking the 1 v. Manufacturing cdte solar cell is cheaper due to its significantly low raw material consumption. High efficiency solution processed sintered cdte nanocrystal. As an absorber material for thinfilmbased solar cells, cdte holds the potentiality to fabricate highefficiency solar cells by means of lowcost technologies. A screenprinted cds cdte solar cell was produced with improved preparation conditions for the carbon electrode, and the influence of the width of the cdte layer on the characteristics of the cell. Potential of cdte thin film solar cells for space applications. About 2,000 tons of cd is thrown away each year in the. The primary routes for increasing cds cdte solar cell efficiency involve increasing free carrier density, reducing bulk and interface recombination, andor reducing back contact barrier height. The first thinfilm technology to be commercialized was amorphous silicon on glass, which was used to power small electronic devices such as calculators.
This paper focuses on the role of the back contact barrier in increasing cell efficiency. Pdf a solar cell is an electronic device which directly converts sunlight into electricity. Furthermore, thin film solar cells containing cadmium telluride hold a substantial advantage over conventional crystalline silicon solar cells. Performance cdte solar cells university of illinois angus rockett copis. We see that cuingase 2 and cdte based solar cells have achieved efficiencies above those for asi cells. Cadmium telluride solar cellscadmium telluride solar cells. In the article, we shall study the temperature and dopinglevel dependence of cdte solar cell performance including excitons with the modi. University of toledo old dominion university robert collins sylvain marsillac this program has explored a number of novel materials for contacts to cdte solar cells in order to reduce the back contact schottky barrier to zero and produce an ohmic contact. Considering that our pv panel should be able to charge a 12v battery to its maximum voltage of about 14v and the overall electrical current voltage characteristic of the photovoltaic generator therefore. Ion imppqgy p pglantation require energy to ionize the dopant. The fact that a variety of deposition technologies can be used to fabricate ef. These cells produce lowcost electricity by absorbing sunlight at nearly the ideal wavelength. Postdeposition processing options for highefficiency sputtered cds cdte solar cells naba r. Solar cell module efficiencies the record lab cell efficiency is 26.
The research on thin film cdte photovoltaic solar cells has been regaining momentum in recent years, due to commercial advances made with regard to cdte technology. Pdf high efficiency cdtecds thin film solar cell researchgate. May 01, 20 the most common semiconductors used in thinfilm solar module production are amorphous silicon asi, cadmium telluride cdte, and copper indium gallium diselenide cigs. Cdte solar cells have the potential to undercut the costs of electricity generated by other technologies, if the opencircuit voltage can be increased beyond 1 v without significant decreases in current. Small area laboratory devices have demonstrated ef. The cell was calibrated by the national renewable energy laboratorys measurements and characterizations facility. Thinfilm solar cells are finally becoming competitive. Numerical simulation shows that the highest efficiency of singlejunction cdscdte solar cell equal to 18. Light shining on the solar cell produces both a current and a voltage to generate electric power. The controlled doping of cdte with cu leads to increased hole density, enhanced carrier lifetime and improved carrier collection in the solar cell. However, in the past decades, the opencircuit voltage has stagnated at around 800900 mv. Pdf simulation and performance study of nanowire cds. Fabrication of cdscdtebased thin film solar cells using.
An overview of solar cell technology stanford university. The solar cell cds cdte obtained in our model has an open circuit voltage of 775 v and a maximum power point of 645 mv. High efficiency cdte and cigs thin film solar cells. Pdf cadmium telluride is a promising photovoltaic material for thinfilm solar cells.
We have done modeling and simulation of thin film cds cdte solar cell and then used. Optimization of electrics parameters cdscdte thin film. Numerical modelling of accharacteristics of cdte and cis. This structure achieved by rotating 90o in the base line structure that suggests high efficiency due to the high current density. The different pv technologies are discussed in part iii. This work involves characterization of cadmium zinc telluride films and solar cells prepared by close spaced sublimation.
Many of the topics that are discussed in this book are also covered in the massive open online course mooc on solar energy delftx, et. Recognize the structure of cdte and cisg thin film cells as well as. Solar cell market size, share industry report, 2022. A cdscdte solar cell of greater than 1 cm2 area with an am1. Cadmium telluride cdte photovoltaics describes a photovoltaic pv technology that is based on the use of cadmium telluride, a thin semiconductor layer designed to absorb and convert sunlight into electricity. Presented at the 2006 ieee 4th world conference on photovoltaic energy conversion wcpec4. Numerical simulation shows that the highest efficiency of singlejunction cds cdte solar cell equal to 18. Cis started evaporating at 600 oc, but only a 20% weight loss was measured at oc steinberger, 1997. Postdeposition processing options for highefficiency. Despite the market remaining dominated by silicon, cdte now accounts for around a 7% market share and is the first of the second generation thin film technologies to effectively make the leap to truly mass deployment. About 20,000 tons of cd are used worldwide each year, about half for nicd batteries. Cadmiumtelluridematerial for thin film solar cells volume issue 10 dieter bonnet, peter meyers skip to main content accessibility help we use cookies to distinguish you from other users and to provide you with a better experience on our websites. Chu introduces a front window layer reducing the thickness of. Electronic properties of cdte cds solar cells as influenced by a buffer layer y.
Cdte solar cells in substrate configuration cdte photovoltaics in the conventional configuration are a proven technology for the large scale production of lowcost currently below 0. Simulation and performance study of nanowire cds cdte solar cell. Figure out the difference of mono and polycrystalline silicon solar cell. Cdte solar cell in a novel configuration tiwari 2004. The melting point of cds is 1750 oc and of gaas is 1238 oc. High efficiency solution processed sintered cdte nanocrystal solar cells. A thin film solar cell is a second generation solar cell that is made by depositing one or more. Pdf a solar cell or photovoltaic cell is designed to convert sunlight into electrical energy through the photoelectric effect. Cds films have been prepared by chemical bath deposition and p. This letter describes the fabrication and characteristics of high. Cadmium telluride pv is the only thin film technology with lower costs than conventional solar.
Optimization of electrics parameters cdscdte thin film solar. At the same time, cdte module efficiency increased from 9% to 18%. The institute of energy conversion iec has been involved in research and development of group iivi semiconductor thin film photovoltaic devices since its founding in 1972. A novel structure of ultrathin cdte solar cells is proposed in this paper that focuses on conversion efficiency. Doping of polycrystalline cdte for highefficiency solar. The best efficiency results reported for three of the more relevant thinfilm solar cell technologies are summarized in table 1 green et al. Chin department of physics, apollo solar energy research center. Other inexpensive solar cells are emerging with high potential such as those based on cuinalse 2. Fraunhofer institute for solar energy systems, ise with support of pse. Our results offer new research directions for solving persistent challenges of cdte photovoltaics. Finally, the paper presents the way forward with next generation cdte based solar cells utilising lowcost materials in their columnar nature in graded bandgap structures. For a device without cds layer, the reflectance spectrum indicates a bandgap of 1. The highest lab efficiency in thin film technology is 23. Cost of power to be further reduced through performance increases and improvements in cell structure or processing.
The result showed a considerable improvement over the 15% efficiency of the reference solar cell. How do buffer layers affect solar cell performance and solar. S1 supporting information the role of back buffer layers and absorber properties for 25% efficient cdte solar cells geethika k. An electronic solar cell model can be considered, as shown in figure 5b, taking into account the effect of the series resistance rs and shunt resistance rsh. At the manufacturing front, the cdte technology is fast paced and moving forward with usbased first solar inc.
In reality, siliconwafer cells achieve, on average, 15 to 25 percent efficiency. A simplified solar cell model and assumptions we consider a simpli. After summarising the history of solar cells in chapter. This design allows cdte solar cells to be made thinner and more. These devices could absorb uv, visible and ir radiation from the solar spectrum and combine impact. A high efficiency ultrathin cdte solar cell for nanoarea. How do buffer layers affect solar cell performance and.
Despite the market remaining dominated by silicon, cdte now accounts for around a 7% market share 1 and is the first of the second generation thin film technologies to effectively make the leap to truly mass deployment. Cadmium telluride solar cells photovoltaic research nrel. Power conversion enhancement of cdscdte solar cell. Cdte solar panel manufacturers thinfilm enf company.
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