Download or read book Development of High efficiency Boron Diffused Silicon Solar Cells written by Arnab Das and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of the proposed research is to develop low-cost, screen-printed 20% efficient silicon solar cells. In the first part of this thesis, a ~19% efficient, screen-printed cell was fabricated using the commercially-dominant aluminum back surface field (Al-BSF) cell structure. Device modeling was then used to determine that increasing the efficiency to 20% required improvements in both back surface passivation and rear reflectance. In the second part of this thesis, a passivated, transparent boron BSF (B-BSF) structure was proposed as a high-throughput method for realizing these improvements. The first step in fabricating the proposed B-BSF cell involved the successful development of a water-based, spin-on solution of boric acid as a low-cost, non-toxic and non-pyrophoric alternative to common boron diffusion sources such as boron tribromide. A review of the literature shows that a common problem with boron diffusion is severe bulk lifetime degradation, with Fe contamination being commonly speculated as the cause. An experimental study was therefore devised in which the impact of boron diffusion and subsequent cell process steps on the bulk lifetime and bulk iron contamination was tracked. From this study, a model for boron diffusion-induced Fe contamination was developed along with methods for gettering Fe from the substrate. A key achievement of this thesis was the discovery of a novel, negatively charged, aluminum-doped spin-on glass (SOG) which can, in a short thermal step, simultaneously getter Fe and provide stable, high-quality passivation of planar, boron-diffused Si surfaces. Since past attempts at achieving low-cost, high-efficiency, boron-diffused cells have suffered from bulk lifetime degradation and difficulties with passivating a boron-diffused Si surface, the Al-doped SOG provides a solution to both challenges. Since a high rear reflectance is important for achieving high-efficiencies, an experimental study of various reflectors was undertaken and a silver colloid material was found which exhibits both high electrical conductivity and Lambertian reflectance>95%. The work on boric acid diffusion, iron gettering, surface passivation and rear reflectors was successfully integrated into a 20.2% efficient, screen-printed, B-BSF cell fabricated on 300 æm thick, p-type float-zone (FZ) Si wafers. Both device theory and modeling was used to show that, due to its well-passivated surfaces, this cell would suffer a large loss in efficiency due to light-induced degradation (LID) if it were fabricated on commercial p-type Czochralski (Cz) Si substrates. Since n-type Si substrates do not suffer from LID, the p-type process was slightly tweaked and applied to n-type FZ wafers, resulting in 20.3% efficient cells on 190 æm thick wafers. Computer modeling shows that both the p-type and n-type cells can maintain efficiencies of 20% for wafers as thin as 100 æm.

Download or read book Nanostructured Solar Cells written by Narottam Das and published by BoD – Books on Demand. This book was released on 2017-02-22 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanostructured solar cells are very important in renewable energy sector as well as in environmental aspects, because it is environment friendly. The nano-grating structures (such as triangular or conical shaped) have a gradual change in refractive index which acts as a multilayer antireflective coating that is leading to reduced light reflection losses over broadband ranges of wavelength and angle of incidence. There are different types of losses in solar cells that always reduce the conversion efficiency, but the light reflection loss is the most important factor that decreases the conversion efficiency of solar cells significantly. The antireflective coating is an optical coating which is applied to the surface of lenses or any optical devices to reduce the light reflection losses. This coating assists for the light trapping capturing capacity or improves the efficiency of optical devices, such as lenses or solar cells. Hence, the multilayer antireflective coatings can reduce the light reflection losses and increases the conversion efficiency of nanostructured solar cells.

Download or read book Silicon Heterojunction Solar Cells written by W.R. Fahrner and published by Trans Tech Publications Ltd. This book was released on 2006-08-15 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: The world of today must face up to two contradictory energy problems: on the one hand, there is the sharply growing consumer demand in countries such as China and India. On the other hand, natural resources are dwindling. Moreover, many of those countries which still possess substantial gas and oil supplies are politically unstable. As a result, renewable natural energy sources have received great attention. Among these, solar-cell technology is one of the most promising candidates. However, there still remains the problem of the manufacturing costs of such cells. Many attempts have been made to reduce the production costs of “conventional” solar cells (manufactured from monocrystalline silicon using diffusion methods) by instead using cheaper grades of silicon, and simpler pn-junction fabrication. That is the ‘hero’ of this book; the heterojunction solar cell.

Download or read book Simulation and Process Development for Ion implanted N type Silicon Solar Cells written by Steven Ning and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As the efficiency potential for the industrial P-type Al-BSF silicon solar cell reaches its limit, new solar cell technologies are required to continue the pursuit of higher efficiency solar power at lower cost. It has been demonstrated in literature that among possible alternative solar cell structures, cells featuring a local BSF (LBSF) have demonstrated some of the highest efficiencies seen to date. Implementation of this technology in industry, however, has been limited due to the cost involved in implementing the photolithography procedures required. Recent advances in solar cell doping techniques, however, have identified ion implantation as a possible means of performing the patterned doping required without the need for photolithography. In addition, past studies have examined the potential for building solar cells on N-type silicon substrates, as opposed to P-type. Among other advantages, it is possible to create N-type solar cells which do not suffer from the efficiency degradation under light exposure that boron-doped P-type solar cells are subject to. Industry has not been able to capitalize on this potential for improved solar cell efficiency, in part because the fabrication of an N-type solar cell requires additional masking and doping steps compared to the P-type solar cell process. Again, however, recent advances in ion implantation for solar cells have demonstrated the possibility for bypassing these process limitations, fabricating high efficiency N-type cells without any masking steps. It is clear that there is potential for ion implantation to revolutionize solar cell manufacturing, but it is uncertain what absolute efficiency gains may be achieved by moving to such a process. In addition to development of a solar specific ion implant process, a number of new thermal processes must be developed as well. With so many parameters to optimize, it is highly beneficial to have an advanced simulation model which can describe the ion implant, thermal processes, and cell performance accurately. Toward this goal, the current study develops a process and device simulation model in the Sentaurus TCAD framework, and calibrates this model to experimentally measured cells. The study focuses on three main tasks in this regard: Task I - Implant and Anneal Model Development and Validation This study examines the literature in solar and microelectronics research to identify features of ion implant and anneal processes which are pertinent to solar cell processing. It is found that the Monte Carlo ion implant models used in IC fabrication optimization are applicable to solar cell manufacture, with adjustments made to accommodate for the fact that solar cell wafers are often pyramidally textured instead of polished. For modeling the thermal anneal processes required after ion implant, it is found that the boron and phosphorus cases need to be treated separately, with their own diffusion models. In particular, boron anneal simulation requires accurate treatment of boron-interstitial clusters (BICs), transient enhanced diffusion, and dose loss. Phosphorus anneal simulation requires treatment of vacancy and interstitial mediated diffusion, as well as dose loss and segregation. The required models are implemented in the Sentaurus AdvancedModels package, which is used in this study. The simulation is compared to both results presented in literature and physical measurements obtained on wafers implanted at the UCEP. It is found that good experimental agreement may be obtained for sheet resistance simulations of implanted wafers, as well as simulations of boron doping profile shape. The doping profiles of phosphorus as measured by the ECV method, however, contain inconsistencies with measured sheet resistance values which are not explained by the model. Task II - Device Simulation Development and Calibration This study also develops a 3D model for simulation of an N-type LBSF solar cell structure. The 3D structure is parametrized in terms of LBSF dot width and pitch, and an algorithm is used to generate an LBSF structure mesh with this parametrization. Doping profiles generated by simulations in Task I are integrated into the solar cell structure. Boundary conditions and free electrical parameters are calibrated using data from similar solar cells fabricated at the UCEP, as well as data from lifetime test wafers. This simulation uses electrical models recommended in literature for solar cell simulation. It is demonstrated that the 3D solar cell model developed for this study accurately reproduces the performance of an implanted N-type full BSF solar cell, and all parameters fall within ranges expected from theoretical calculations. The model is then used to explore the parameter space for implanted N-type local BSF solar cells, and to determine conditions for optimal solar cell performance. It is found that adding an LBSF to the otherwise unchanged baseline N-type cell structure can produce almost 1% absolute efficiency gain. An optimum LBSF dot pitch of 450um at a dot size of 100um was identified through simulation. The model also reveals that an LBSF structure can reduce the fill factor of the solar cell, but this effect can be offset by a gain in Voc. Further efficiency improvements may be realized by implementing a doping-dependent SRV model and by optimizing the implant dose and thermal anneal. Task III - Development of a Procedure for Ion Implanted N-type LBSF Cell Fabrication Finally, this study explores a method for fabrication of ion-implanted N-type LBSF solar cells which makes use of photolithographically defined nitride masks to perform local phosphorus implantation. The process utilizes implant, anneal, and metallization steps previously developed at the UCEP, as well as new implant masking steps developed in the course of this study. Although an LBSF solar cell has not been completely fabricated, the remaining steps of the process are successfully tested on implanted N-type full BSF solar cells, with efficiencies reaching 20.0%.

Download or read book Development of pulsed processes for the manufacture of solar cells written by Spire Corporation and published by . This book was released on 1978 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Diffused Surfaces for High Efficiency Silicon Solar Cells written by Achim Kimmerle and published by . This book was released on 2015 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development and Characterization of Resource saving Doping Processes for Industrial Silicon Solar Cells written by Marius Meßmer and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Thermal processes account for a significant share of process cost and energy consumption during the manufacturing of passivated emitter and rear (PERC) and tunnel oxide passivated contacts (TOPCon) solar cells. This thesis investigates high throughput approaches for the thermal processes diffusion and/or oxidation in the manufacturing sequence of PERC and TOPCon solar cells. This is achieved by increasing the number of wafers in the process chamber by using wafer stacks with the wafer surfaces in direct contact rather than classical quartz boats with several mm spacing. Compared to state-of-the-art processing, the throughput can be drastically increased which makes the manufacturing more cost-effective and sustainable. For PERC solar cells, the high temperature stack oxidation (HiTSOx) approach has been developed. This approach combines a shortened phosphorus oxychloride (POCl3) diffusion with a stacked oxidation process. Here, the stack oxidation generates the final emitter doping profile from the phosphorus already incorporated in the silicon after the POCl3 diffusion through dopant redistribution and activation. Simultaneously a silicon dioxide surface passivation layer forms on the wafer surface. With this approach, PERC solar cells are fabricated that feature a similar energy conversion efficiency compared to state-of-the-art processing with 22.2%. With HiTSOx, the cost of ownership (COO) of the thermal processes is reduced by 44%, saving 50% of the specific power consumption. The oxide layer grown during the HiTSOx process exhibits a high uniformity of below 6% standard deviation over the surface of a 156.75 mm sized wafer. This is a surprising result taking into account that the wafers are directly stacked during the process. Therefore, a model describing the new oxidation process was developed. Numerical simulation of the oxide growth and gas flow within the gap between the stacked wafers reveal that the consumption of oxygen creates a reduced local pressure in the wafer gap, forcing further oxygen to flow into the wafer gap. The numerical simulation is verified by special experiments. For TOPCon solar cells, a stacked boron diffusion process is developed. Prior to the stack diffusion process, a borosilicate glass layer is deposited by atmospheric chemical vapor deposition (APCVD) as a dopant source. The above-described uniform surface oxidation in the wafer gap yields a homogeneous doping result, despite a strong sensitivity of boron diffusion to oxygen. In addition, the results indicate that the temperature uniformity in the wafer stack is of high importance. Using stack diffusion, TOPCon solar cells with energy conversion efficiency above 23% are fabricated only slightly below the references fabricated with the classical process. Further, the COO of the doping process is reduced by 19 to 25%, depending on the borosilicate glass deposition technology, and specific energy consumption by up to 55%, enabling a more sustainable solar cell manufacturing

Download or read book Ion Implantation for High efficiency Silicon Solar Cells written by Ralph Müller and published by Fraunhofer Verlag. This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The profitability of the whole photovoltaic system can be effectively increased by the use of advanced silicon solar cells with a higher conversion efficiency potential and new technologies are needed to keep the fabrication effort low. Ion implantation allows for single side and even patterned doping of silicon wafers, so this technique could help to simplify the process chain of complex high-efficiency silicon solar cells. In this thesis, the suitability of ion implantation for the fabrication of modern solar cells was investigated. The implantation of mass-separated boron or phosphorus ions and subsequent furnace annealing was used to study the charge carrier recombination due to implantation defects and obtain doping profiles for an evaluation at the device level. Furthermore, novel process sequences combining ion implantation and furnace diffusion for the simplified doping of back-junction back-contact cells were developed and evaluated with respect to the influence of a reverse breakdown and a weak front-side doping on the solar cell performance.

Download or read book High Efficiency Silicon Solar Cells written by Martin A. Green and published by Trans Tech Publications Ltd. This book was released on 1987-01-01 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: The early chapters comprehensively review the optical and transport properties of silicon. Light trapping is described in detail. Limits on the efficiency of silicon cells are discussed as well as material requirements necessary to approach these limits. The status of current approaches to passifying surfaces, contacts and bulk regions is reviewed. The final section of the book describes the most practical approaches to the fabrication of high-efficiency cells capable of meeting the efficiency targets for both concentrated and non-concentrated sunlight, including a discussion of design and processing approaches for non-crystalline silicon.

Download or read book Solar Energy Update written by and published by . This book was released on 1981 with total page 688 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book N Type Crystalline Silicon Photovoltaics written by Delfina Muñoz and published by IET. This book was released on 2023-03-06 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: n-type solar cells are less prone to defects and degradation compared to p-type solar cells. This makes n-type solar cells more effective, but manufacturing challenges remain. This reference conveys the state of research and development for n-type solar cells.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1987 with total page 938 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Solar Cells and Modules written by Arvind Shah and published by Springer Nature. This book was released on 2020-07-16 with total page 357 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives a comprehensive introduction to the field of photovoltaic (PV) solar cells and modules. In thirteen chapters, it addresses a wide range of topics including the spectrum of light received by PV devices, the basic functioning of a solar cell, and the physical factors limiting the efficiency of solar cells. It places particular emphasis on crystalline silicon solar cells and modules, which constitute today more than 90 % of all modules sold worldwide. Describing in great detail both the manufacturing process and resulting module performance, the book also touches on the newest developments in this sector, such as Tunnel Oxide Passivated Contact (TOPCON) and heterojunction modules, while dedicating a major chapter to general questions of module design and fabrication. Overall, it presents the essential theoretical and practical concepts of PV solar cells and modules in an easy-to-understand manner and discusses current challenges facing the global research and development community.

Download or read book Electricity from Photovoltaic Solar Cells High efficiency solar cells written by and published by . This book was released on 1986 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book ERDA Research Abstracts written by United States. Energy Research and Development Administration and published by . This book was released on 1976 with total page 1040 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1993 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of High efficiency Solar Cells on Silicon WEB written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: