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. In reality, siliconwafer cells achieve, on average, 15 to 25 percent efficiency. Thin film cds cdte has long been regarded as one promising choice for the development of costeffective and reliable solar cells. The cdte ncs in pyridine are stirred under nitrogen overnight on a hotplate set to 105c.
Thinfilm solar cells, a second generation of photovoltaic pv solar cells. Simulation of the efficiency of cdscdte tandem multi. Generally, the back contact is made by depositing a few nanometres of copper onto an etched cdte surface, where a thin layer of tellurium is formed. Most of the thin film solar cells and asi are second generation solar cells, and are more economical as compared to the first generation silicon wafer solar cells. Pv solar cells based on cdte represent the largest segment of commercial thin. Cdte solar cells are also expected to exhibit good stability but not much was reported up to now 3. The high specific power is an important issue for space solar cells. Recent progress on solutionprocessed cdte nanocrystals solar. Feb 23, 2016 leading cadmiumtelluride cdte thinfilm producer first solar has set a new world record research cell conversion efficiency of 22. Doping of polycrystalline cdte for highefficiency solar. These cells produce lowcost electricity by absorbing sunlight at nearly the ideal wavelength. Cdcl2 activation step cdcl2 activation is vital to high efficiency cdte solar cells typically converts a cell of 10% a thin layer 20200nm of cdcl2 is deposited on the cdte free back surface sample then annealed in a tube furnace under an air ambient can also be done with mgcl2 as an alternative.
Pdf cdte solar cells with opencircuit voltage breaking the. Fabricate and test cdtesi homojunction solar cells. Atomicscale study of grain boundary structures in polycrystalline cdte solar cells using abberationcorrected stem volume 19 issue s2 t. The most common cdte solar cells consist of a simple pn heterojunction structure containing a pdoped cdte layer matched with an ndoped cadmium sulfide cds layer, which acts as a window layer. Cdte is of low cost thin film photovoltaic cells because of its direct band gap and have high absorption coefficient. Design of a high efficiency cdscdte solar cell with. Photovoltaic characteristics of low concentration cdte solar cells article pdf available in iop conference series materials science and engineering 556. In order to yield high power conversion efficiency.
Studies of sputtered cdte and cdse solar cells book, 2012. Thin film cdscdte has long been regarded as one promising choice for the development of costeffective and reliable solar cells. By using atomicresolution zcontrast imaging and xray spectroscopy in a scanning transmission electron microscopes scientists have successfully been able to explore dislocations in the binary iivi semiconductor cdte, commercially used in thinfilm photovoltaics. One of the central areas of investigation concerning cdscdte cells is the problem of a schottky barrier at the back contact. Pdf photovoltaic characteristics of low concentration cdte. A big step forward in cost reduction is expected through the growth of solar cells on flexible metal. Cdte could be doped with both n and p type materials using a large number of of preparation methods techniques such as vacuum deposition. Model the photon absorption and electrical carrier transport in cdtesi solar cells and their efficiencies. Cadmium telluride cdte has long been recognized as a strong candidate for thin film solar cell applications. The role of back buffer layers and absorber properties for. For example, copper cu was initially believed to be a key element for the formation of the back contact, until studies of impurity distribution in cdte cds solar cells indicated that this element accumulates at the. Herein, a convenient aqueous route was adopted to synthesize cdte core qds for the construction of typeii coreshell qd sensitizers. First solars cdte module technology performance, life cycle, health and safety impact assessment stellenbosch university centre for renewable and sustainable energy studies dr. It is mainly used as the semiconducting material in cadmium telluride photovoltaics and an infrared optical window.
Cigs solar cell on a flexible plastic backing and rigid cdte panels mounted on a supporting structure. Dohyoung kwon cdte has recently become the most commercially successful polycrystalline thin film solar module material. 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. One of the major problems for cdte solar cells is the difficulty in obtaining low and stable. These are called passivated emitter and rear cells perc. Pdf simulation of cadmium telluride solar cells structure. We have developed a novel cucl 2 wet deposition method to insert minimal amount of cu in the cdte.
First solar pushes cdte cell efficiency to record 22. Heben wright center for photovoltaics innovation and commercialization, department of physics and. Leading cadmiumtelluride cdte thinfilm producer first solar has set a new world record research cell conversion efficiency of 22. Cadmium telluride solar cells use lowcost manufacturing technology to produce lowcost cells.
Cdte solar panels are now at parity with polycrystalline silicon for performance and cost. Traditional siliconwafer solar panels require a complex, timeconsuming manufacturing process that drives up the perwatt cost of electricity. Cadmium telluride solar cells photovoltaic research nrel. Thinfilm cells could blanket the roofs or form facades of buildings across cities. Wehaveinvestigatedcudistribution in cdte solar cells in substrate con. Pdf a solar cell or photovoltaic cell is designed to convert sunlight into electrical energy through the photoelectric effect. Could cdte pv modules pollute the environment brookhaven. In addition to an advantageous energy gap, cdte also has two other beneficial qualities. Dear colleagues, 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. A range of the deposition parameters is included in table 1. Cdte quantum dots qds with a narrow band gap and high conduction band cb edge provide great potential for the fabrication of qd sensitized solar cells qdscs. Study of efficiencies cdtecds photovoltaic solar cell. 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. Cdte solar cells with opencircuit voltage breaking the 1.
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. Light shining on the solar cell produces both a current. This solution is precipitated with hexane, redispersed in pyridine, and precipitated once again using hexane. High efficiency cdte and cigs thin film solar cells. In summary, the recycling of cdte thin film solar cells is a complex issue that requires careful attention to global, federal, and local regulations, materials economics, and experiences of comparable industries. Thin film solar cells based on polycrystal line cadmium telluride cdte reached record efficien cies of 16. 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. Wavelength dependent performance of cdte solar cells.
High efficiency solution processed sintered cdte nanocrystal. As demonstrated by the top performing cdte devices, cu is necessary for high efficiency. However, this treatment step behaves differently on hightemperaturegrown cdte than on lowertemperaturegrown cdte layers such as those grown by sputtering. Furthermore, the surface roughness of the cdte nc thin film was small. Power conversion enhancement of cdscdte solar cell. Cadmium telluride photovoltaics 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 cadmium telluride pv is the only thin film technology with lower costs than conventional solar. Pdf cdte solar cells with opencircuit voltage breaking.
Accumulation of cu at the cdteback contact interface and in the ntype cds is observed. Pdf achievements and challenges of cdscdte solar cells. Cadmium telluride cdte thin film for photovoltaic applications. If thinfilm solar cells achieve their full potential, however, its easy to imagine a future where solar power is as ubiquitous as, well, sunlight. Its low cost, largearea solar module is reshaping the silicondominated solar panel market. There are health concerns with the use of cadmium in thinfilm solar cells. Cdte solar cells with opencircuit voltage breaking the 1 v. Fabricate cdte pn homojunctions and characterize them with iv and cv. Light photon energy electric energy silicon solar photovoltaic cells a device made of semiconductor materials that produce electricity under light a pn junction is created in silicon by a doping process. The efficiency of cdte solar cells has reached just more than 15 percent, and cigs solar cells have reached 20 percent efficiency. Doe supports innovative research focused on overcoming the current technological and commercial barriers for cadmium telluride cdte solar cells.
Apr 04, 2016 cdcl2 activation step cdcl2 activation is vital to high efficiency cdte solar cells typically converts a cell of 10% a thin layer 20200nm of cdcl2 is deposited on the cdte free back surface sample then annealed in a tube furnace under an air ambient can also be done with mgcl2 as an alternative. Cadmium telluride cdte solar cells have quietly established themselves as a mass market pv technology. Ion imppqgy p pglantation require energy to ionize the dopant. Cdte is a iivi group of semiconductor materials with a moderate band gap of 1. This brings to high efficiencies but with a rollover. Solar cell market size, share industry report, 2022. Research groups use a variety of processes to fabricate thinfilm cdscdte cells, including physical vapor deposition, chemical vapor deposition, and rf diode sputtering. Cadmium telluride pv is the only thin film technology with lower costs than conventional solar cells made of crystalline silicon in multikilowatt systems. Exceeding 20% efficiency with in situ group v doping in.
Since the record effi ciency of such type solar cells is considerably lower than the theoretical limit of 28% 30% 3, the performance. The additional layer decreases the recombination rate on the back. So far, more than 20 gw of cdtebased solar technology has been installed, with. Measurement of the cdte minority carrier recombination lifetimes. First solars cdte module technology performance, life. With the data, we can save the variations of jsc, voc, ff and analyze the efficiency the jv characteristic modeled in figure 1 uses the values in table 1.
Potential of cdte thin film solar cells for space applications. It is usually sandwiched with cadmium sulfide to form a pn junction solar pv cell. A thin film of cdte with thickness around 2 m will absorb almost all the incident solar radiation. Cadmium telluride cdte is a stable crystalline compound formed from cadmium and tellurium. Cadmium telluride is a promising photovoltaic material for thinfilm solar cells. Since the record effi ciency of such type solar cells is considerably lower than the theoretical limit of 28%. Due to its basic optical, electronic, and chemical properties, cdte can become the base material for highefficiency, lowcost thin film solar cells using robust, highthroughput manufacturing techniques. A barrierfree back contact in cdtecds solar cells is fundamental for obtaining high efficiency devices. Thinfilm solar cells are commercially used in several technologies, including cadmium telluride cdte, copper indium gallium diselenide cigs, and amorphous thinfilm silicon asi, tfsi. As stated earlier, most pv cells are disposed in municipal landfills. It is well known theoretically, that for the cadmium telluride cdte solar cells, the minimal thickness of the cdte film, required to absorb 99% of incident photons.
New research breakthrough results may lead to eventual improvement in the conversion efficiency of cdte solar cells. The efficiency of the cdtecds solar cell reached 21. Pdf a solar cell is an electronic device which directly converts sunlight into electricity. Cdte solar cells with opencircuit voltage breaking the 1 v barrier article pdf available in nature energy 1. However, the thickness of cdte nc solar cells was significantly lower than those cdte solar cells prepared by the css method. The temperature variation affects these parameters and, hence, the performance of solar cells 18. However, it is a fast diffuser degrading the cell in the long term. Manufacturing cdte solar cell is cheaper due to its significantly low raw material consumption.
Cdte solar panel manufacturers companies involved in cdte solar panel production, a key thinfilm panel technology. Below are a list of current projects, summary of the benefits, and discussion of the production and manufacturing techniques. Cadmiumtelluridematerial for thin film solar cells. In this way, a cu xte film is obtained fo rming an ohmic contact with cdte. Polycrystalline cdscdte solar cells al compaan distinguished university professor of physics, emeritus lecture for hebenellingson solar cells class mhmarch 15 201215, 2012 1. Atomicscale study of grain boundary structures in poly. Production method for cdte solar cells in substrate. Transitioning from the lab to manufacturing has been much more difficult than anticipated. Rf magnetron triode sputtering of cdte and znte films and. Annealing of the cdstco transparent conductive oxide bilayer in both oxidising and reducing ambients was investigated in order to study changes in the electrical properties of the incds. Postdeposition processing options for highefficiency sputtered cdscdte solar cells naba r. Cdcl2 activation is a wellknown method to passivate grain boundaries for cdte solar cells.
Properties for 25% efficient cdte solar cells geethika k. Pdf cadmium telluride cdte is the most commercially successful thinfilm photovoltaic technology. 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. Cdte evidence of some voids near the cdscdte interface au evidence of some voids near the cdscdte interface high cu concentration at interface and in the au layer little evidence of cu along grain boundaries grain boundaries 25 edse edsd t e l d l cdte a curich layer 0 5 10 15 20 eds intensity cs edsf cu k c u 15 20 25 e. In crystalline silicon solar cells, manufacturers have started to modify film structures to incorporate a passivated layer. Cdte solar panel manufacturers thinfilm enf company. Figure 1 presents a stateoftheart cdte solar cell that is simi. Superstrate the superstrate configuration is used in most cdte solar cells this is due to the particular difficulty in making the rear contact we will see why the back contact is usually deposited at the end of the cell to have a better control superstrate configuration. Design of a thin film cdte solar cell sciencedirect. Current cdte panels contain approximately 6 gm2, resulting in cadmium emissions of 0. Furthermore, thin film solar cells containing cadmium telluride hold a substantial advantage over conventional crystalline silicon solar cells.
Due to its basic optical, electronic, and chemical properties, cdte can become the base material for highefficiency, lowcost thin film solar cells using robust, high. Cdte based quantum dot sensitized solar cells with. As a comparison, typical commercial siliconbased solar cells require an absorber thickness of around 200 mm whereas their cdte equivalents are less than 5 mm thick. Znte thickness for efficient cdte thinfilm solar cells prepared by the css method was about 100 nm. The ncdspcdte solar cell has been researched for many years now. Thinfilm solar cells are finally becoming competitive. 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. However, the performance and reproducibility of devices has been limited by the. Cdtecds thin film in solar cell linkedin slideshare. Highefficiency ctoztocdscdte polycrystalline thinfilm solar.