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Photovoltaic Devices Based On Cuin1 Xgaxse2 Nanocrystal Inks
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Book Synopsis Photovoltaic Devices Based on Cu(In1-xGax)Se2 Nanocrystal Inks by : Vahid Atar Akhavan
Download or read book Photovoltaic Devices Based on Cu(In1-xGax)Se2 Nanocrystal Inks written by Vahid Atar Akhavan and published by . This book was released on 2011 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin film copper indium gallium selenide (CIGS) solar cells have exhibited single junction power conversion efficiencies above 20% and have been commercialized. The large scale production of CIGS solar cells, however, is hampered by the relatively high cost and poor stoichiometric control of coevaporating tertiary and quaternary semiconductors in high vacuum. To reduce the overall cost of production, CIGS nanocrystals with predetermined stoichiometry and crystal phase were synthesized in solution. Colloidal nanocrystals of CIGS provide a novel route for production of electronic devices. Colloidal nanocrystals combine the well understood device physics of inorganic crystalline semiconductors with the solution processability of amorphous organic semiconductors. This approach reduces the overall cost of CIGS manufacturing and can be used to fabricate solar cells on flexible and light-weight plastic substrates. As deposited CIGS nanocrystal solar cells were fabricated by ambient spray-deposition. Devices with efficiencies of 3.1% under AM1.5 illumination were fabricated. Examining the external and internal quantum efficiency spectrums of the devices reveal that in nanocrystal devices only the space charge region is actively contributing to the extracted photocurrent. The device efficiency of the as-deposited nanocrystal films is presently limited by the small crystalline grains (H"15 nm) in the absorber layer and the relatively large interparticle spacing due to the organic capping ligands on the nanocrystal surfaces. Small grains and large interparticle spacing limits high density extraction of electrons and holes from the nanocrystal film. A Mott-Schottky estimation of the space charge region reveals that only 50 nm depth of the nanocrystalline absorber is effectively contributing to the photogenerated current. One strategy to improve charge collection involves increased space charge region for extraction by vertical stacking of diodes. A much longer absorption path for the photons exists in the space charge region with the stacked devices, increasing the probability that the incident radiation is absorbed and then extracted. This method enables an increase in the collected short circuit current. The overall device efficiency, however, suffers with the increased series resistance and shunt conductance of the device. Growth of nanocrystal grains was deemed necessary to achieve power conversion efficiencies comparable to vapor deposited CIGS films. Simple thermal treatment of the nanocrystal layers did not contribute to the growth of the crystalline grain size. At the same time, because of the loss of selenium and increased trap density in the absorber layer, there was a measurable decrease in device efficiency with thermal processing. For increased grain size, the thermal treatment of the absorber layer took place in presence of compensating amounts of selenium vapor. The process of selenization, as it is called, took place at 500°C in a graphite box and led to an increase of the grain size from 15 nm to several microns in diameter. Devices with the increased grain size yielded efficiencies up to 5.1% under AM1.5 radiation. Mott-Schottky analysis of the selenized films revealed a reduction in doping density and a comparable increase in the space-charge region depth with the increased grain size. The increased collection combined with the much higher carrier mobility in the larger grains led to achieved Jsc values greater than 20 mA/cm2. Light beam induced current microscopy (LBIC) maps of the devices with selenized absorber layers revealed significant heterogeneity in photogenerated current. Distribution of current hotspots in the film corresponded with highly selenized regions of the absorber films. In an effort to improve the overall device efficiency, improvements in the selenization process are necessary. It was determined that the selenization procedure is dependent on the selenization temperature and processing environment. Meanwhile, the reactor geometry and nanocrystal inks composition played important roles in determining selenized film morphology and the resulting device efficiency. Further work is necessary to optimize all the parameters to improve device efficiency even further.
Book Synopsis Thin Film CuIn1-xGaxSe-Based Solar Cells Prepared from Solution-Based Precursors by :
Download or read book Thin Film CuIn1-xGaxSe-Based Solar Cells Prepared from Solution-Based Precursors written by and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have fabricated high-efficiency thin-film CuIn1-xGaxSe2 (CIGS)-based photovoltaic devices from solution-based electroplated (EP) and auto-plated (AP) precursors. As-deposited precursors are Cu-rich CIGS. Compositions were adjusted to CuIn1-xGaxSe2 with additional In and Ga by physical vapor deposition (PVD) to the EP and AP precursor films. Auger analysis and grazing incident X-ray diffraction(GIXRD) were performed on devices prepared from EP and AP precursor films. We have also analyzed and compared EP, AP, and an PVD CIGS device by deep-level transient spectroscopy (DLTS).
Book Synopsis Nanomanufacturing Handbook by : Ahmed Busnaina
Download or read book Nanomanufacturing Handbook written by Ahmed Busnaina and published by CRC Press. This book was released on 2017-12-19 with total page 489 pages. Available in PDF, EPUB and Kindle. Book excerpt: Breakthroughs in nanotechnology have been coming at a rapid pace over the past few years. This was fueled by significant worldwide investments by governments and industry. But if these promising young technologies cannot begin to show commercial viability soon, that funding is in danger of disappearing as investors lose their appetites and the economic and scientific promise of nanotechnology may not be realized. Scrutinizing the barriers to commercial scale-up of nanotechnologies, the Nanomanufacturing Handbook presents a broad survey of the research being done to bring nanotechnology out of the laboratory and into the factory. Current research into nanotechnology focuses on the underlying science, but as this forward-looking handbook points out, the immediate need is for research into scale-up, process robustness, and system integration issues. Taking that message to heart, this book collects cutting-edge research from top experts who examine such topics as surface-programmed assembly, fabrication and applications of single-walled carbon nanotubes (SWNTs) including nanoelectronics, manufacturing nanoelectrical contacts, room-temperature nanoimprint and nanocontact technologies, nanocontacts and switch reliability, defects and surface preparation, and other innovative, application-driven initiatives. In addition to these technical issues, the author provides a survey of the current state of nanomanufacturing in the United States—the first of its kind—and coverage also reaches into patenting nanotechnologies as well as regulatory and societal issues. With timely, authoritative coverage accompanied by numerous illustrations, the Nanomanufacturing Handbook clarifies the current challenges facing industrial-scale nanotechnologies and outlines advanced tools and strategies that will help overcome them.
Book Synopsis Advanced Ceramic Coatings for Emerging Applications by : Ram Gupta
Download or read book Advanced Ceramic Coatings for Emerging Applications written by Ram Gupta and published by Elsevier. This book was released on 2023-05-20 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Ceramic Coatings for Emerging Applications covers new developments in automotive, construction, electronic, space and defense industries. The book is one of four volumes that together provide a comprehensive resource in the field of Advanced Ceramic Coatings, also including titles covering fundamentals, manufacturing and classification, energy and biomedical applications. These books will be extremely useful for academic and industrial researchers and practicing engineers who need to find reliable and up-to-date information about recent progresses and new developments in the field of advanced ceramic coatings. These books will also be of value to early career scientists providing background knowledge to the field. Smart ceramic coatings containing multifunctional components are now finding application in transportation and automotive industries, in electronics, and energy, sectors, in aerospace and defense, and in industrial goods and healthcare. Their wide application and stability in harsh environments are only possible due to the stability of the inorganic components that are used in ceramic coatings. Provides comprehensive coverage of emerging applications in advanced ceramic coatings Features the latest progress and recent technological developments Includes comparisons to other coatings types (e.g., polymers, metals and enamel) to demonstrate potential, limitations and differences Contains extensive case studies and worked examples
Book Synopsis Sintering of CU(In,Ga)Se2 Nanocrystal Films for Photovoltaics by : Taylor Bryan Harvey
Download or read book Sintering of CU(In,Ga)Se2 Nanocrystal Films for Photovoltaics written by Taylor Bryan Harvey and published by . This book was released on 2014 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low cost solar cells are needed to increase availability and reliability of electricity throughout the world. Spray deposition of Cu(In,Ga)Se2 (CIGS) nanocrystal inks is a promising route to low cost photovoltaics(PVs). CIGS nanocrystal inks have been used to fabricate solar cells with 3.1% power conversion efficiency (PCE) without any heat treatment, but are limited by poor charge transport. Sintering the nanocrystals into a polycrystalline film improves charge transport and device performance. Two sintering methods are investigated here: selenization and photonic curing. The nanocrystal films can be sintered by annealing the films in a Se environment, also known as selenization. The selenized device morphology and efficiency is influenced by the starting nanocrystal composition. A Se/Carbon layer deriving from the organic ligand decreases device efficiency, but is eliminated by annealing the nanocrystal films in Ar before the selenization treatment. In addition to eliminating the Se/Carbon layer, the pre-selenization anneal drives Na from the soda-lime glass substrate into the film and improves grain growth. Devices with efficiencies above 7.0% are fabricated using a multi-step deposition and sintering process. To simplify device fabrication, a single-step, scalable deposition is demonstrated using fully automated, ultrasonic spray coating. The ultrasonic spray deposition is highly sensitive to the nanocrystal ink organic content, and optimization of the nanocrystal synthesis wash procedure leads to highly uniform, reflective nanocrystal films. Devices fabricated from these films achieve 6.6% efficiency after selenization. The use of rapid pulses of broadband light, or photonic curing, is an alternative sintering method that is compatible with roll-to-roll fabrication and does not use high temperature processing. A wide range of pulse energy is used to treat nanocrystal films after spray deposition on three different back contact materials. Nanocrystal dewetting and agglomeration was observed after photonic curing of the films on a Mo contact, but is reduced significantly by using Au or MoSe2/Mo back contacts. Low energy pulses remove the organic capping ligand and bring the nanocrystals into close electrical contact, leading to devices exhibiting multiple exciton generation and extraction. Higher energy pulses sinter the nanocrystal layer and sintered nanocrystal photovoltaic devices are demonstrated.
Book Synopsis The Physics of Ultrathin CdTe Based Photovoltaic Devices from Nanoparticle Inks by : Christopher E. France
Download or read book The Physics of Ultrathin CdTe Based Photovoltaic Devices from Nanoparticle Inks written by Christopher E. France and published by . This book was released on 2011 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Thin Film Nanomaterials: Synthesis, Properties and Innovative Energy Applications by : Sampat G. Deshmukh
Download or read book Thin Film Nanomaterials: Synthesis, Properties and Innovative Energy Applications written by Sampat G. Deshmukh and published by Bentham Science Publishers. This book was released on 2024-07-25 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin Film Nanomaterials: Synthesis, Properties and Innovative Energy Applications provides a comprehensive overview of the synthesis, properties, and cutting-edge applications of thin film nanomaterials. Each chapter explores different aspects of thin film synthesis and its application in energy devices, showcasing different metal-based and carbon nanomaterials . The book begins with a discussion on the synthesis and characterization of cadmium and zinc sulphide thin films for opto-electronics energy devices. Subsequent chapters delve into critical reviews of CIGS thin film nanomaterials, deposition techniques for metal oxide nanocomposite films, and nanostructured TiO2@carbon films for photocatalytic applications. Bandgap engineering, optical properties of composite films, and recent advancements in metal oxide thin films are also covered. Additionally, the synthesis and characteristics of iron oxide films for solar cell and green energy storage applications are discussed. Chapters on challenges and future prospects of CNT-based cathode emitters and advanced characterizations of nanocrystalline ferrimagnetic thin films provide valuable insights into emerging technologies. This book is an essential resource for professors, scientists, engineers, research scholars, postdocs, and undergraduate/graduate students seeking to explore the forefront of nanomaterials and their applications in energy systems.
Book Synopsis Renewable Energy - Volume 1: Solar, Wind, and Hydropower by : Abdul Ghani Olabi
Download or read book Renewable Energy - Volume 1: Solar, Wind, and Hydropower written by Abdul Ghani Olabi and published by Elsevier. This book was released on 2023-04-29 with total page 580 pages. Available in PDF, EPUB and Kindle. Book excerpt: Renewable Energy - Volume 1: Solar, Wind, and Hydropower: Definitions, Developments, Applications, Case Studies, and Modelling and Simulation is a comprehensive resource for those wanting an authoritative volume on the significant aspects of these rapidly growing renewable technologies. Providing a structured approach to the emerging technologies and advances in the implementation of solar, wind and hydro energy, the book offers the most requested and desirable practical elements for the renewable industry. Sections cover definitions, applications, modeling and analysis through case study and example. This coordinated approach allows for standalone, accessible, and functioning chapters dedicated to a particular energy source, giving researchers and engineers an important and unique consolidated source of information on all aspects of these state-of-the-art fields. Includes in-depth and up-to-date explanations for the latest developments in Solar, Wind and Hydropower Presents a uniquely, thematically arranged book with structured content that is easily accessible and usable Provides extensively illustrated and supported content, including multimedia components like short videos and slideshows for greater examples and case studies
Book Synopsis Low Cost Processing of CuInSe2 Nanocrystals for Photovoltaic Devices by : Carl Jackson Stolle
Download or read book Low Cost Processing of CuInSe2 Nanocrystals for Photovoltaic Devices written by Carl Jackson Stolle and published by . This book was released on 2015 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: Semiconductor nanocrystal-based photovoltaics are an interesting new technology with the potential to achieve high efficiencies at low cost. CuInSe2 nanocrystals have been synthesized in solution using arrested precipitation and dispersed in solvent to form a "solar ink". The inks have been deposited under ambient conditions to fabricate photovoltaic devices with efficiency up to 3%. Despite the low cost spray coating deposition technique, device efficiencies remain too low for commercialization. Higher efficiencies up to 7% have been achieved using a high temperature selenization process, but this process is too expensive. New nanocrystal film treatment processes are necessary which can improve the device efficiency at low cost. To this end, CuInSe2 nanocrystals were synthesized using a diphenyl phosphine:Se precursor which allows for precise control over the nanocrystal size. The size is controlled by changing the temperature of the reaction. The smallest size nanocrystals demonstrated extremely high device open circuit voltage. Ligand exchange procedures were used to replace the insulating oleylamine capping ligand used during synthesis with more conductive halide ions or inorganic chalcogenidometallate cluster (ChaM) ligands. These ligands led to improved charge transport in the nanocrystal films. A high-intensity pulsed light processing technique known as photonic curing was used which allows for high temperature sintering of nanocrystal films on temperature-sensitive substrates. High energy pulses cause the nanocrystals to sinter into large grains, primarily through melting and resolidification. The choice of metal back contact has a dramatic effect on the final film morphology, with Au and MoSe2 back contacts providing much better adhesion with the CuInSe2 than Mo back contacts. Nanocrystal sintering without melting can be achieved by replacing the oleylamine ligands with ChaM ligands prior to photonic curing. Low energy photonic curing pulses vaporize the oleylamine ligands without inducing sintering or grain growth. This greatly improved nanocrystal coupling and interparticle charge transport. Multiexcitons were successfully extracted from these nanocrystal films and external quantum efficiencies over 100% were observed. Transient absorption spectroscopy was used to study the multiexciton generation process in CuInSe2 nanocrystal films and colloidal suspensions. The multiexciton generation efficiency, threshold, and Auger lifetimes for CuInSe2 compare well with other nanocrystal materials.
Book Synopsis Photovoltaic Devices Employing Ternary PbSxSe1-x Nanocrystals by :
Download or read book Photovoltaic Devices Employing Ternary PbSxSe1-x Nanocrystals written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report solar cells based on highly confined nanocrystals of the ternary compound PbSxSe1-x. Crystalline, monodisperse alloyed nanocrystals are obtained using a one-pot, hot injection reaction. Rutherford back scattering and energy filtered transmission electron microscopy suggest that the S and Se anions are uniformly distributed in the alloy nanoparticles. Photovoltaic devices made using ternary nanoparticles are more efficient than either pure PbS or pure PbSe based nanocrystal devices.
Book Synopsis Thin Film Solar Cells by : Jef Poortmans
Download or read book Thin Film Solar Cells written by Jef Poortmans and published by John Wiley & Sons. This book was released on 2006-10-02 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt: Thin-film solar cells are either emerging or about to emerge from the research laboratory to become commercially available devices finding practical various applications. Currently no textbook outlining the basic theoretical background, methods of fabrication and applications currently exist. Thus, this book aims to present for the first time an in-depth overview of this topic covering a broad range of thin-film solar cell technologies including both organic and inorganic materials, presented in a systematic fashion, by the scientific leaders in the respective domains. It covers a broad range of related topics, from physical principles to design, fabrication, characterization, and applications of novel photovoltaic devices.
Book Synopsis Solar Energy Conversion and Storage by : Suresh C. Ameta
Download or read book Solar Energy Conversion and Storage written by Suresh C. Ameta and published by CRC Press. This book was released on 2015-11-05 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar Energy Conversion and Storage: Photochemical Modes showcases the latest advances in solar cell technology while offering valuable insight into the future of solar energy conversion and storage. Focusing on photochemical methods of converting and/or storing light energy in the form of electrical or chemical energy, the book:Describes various t
Book Synopsis Novel Photovoltaic Devices Using Ferroelectric Material and Colloidal Quantum Dots by : Young Hun Paik
Download or read book Novel Photovoltaic Devices Using Ferroelectric Material and Colloidal Quantum Dots written by Young Hun Paik and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As the global concern for the financial and environmental costs of traditional energy resources increases, research on renewable energy, most notably solar energy, has taken center stage. Many alternative photovoltaic (PV) technologies for 'the next generation solar cell' have been extensively studied to overcome the Shockley-Queisser 31% efficiency limit as well as tackle the efficiency vs. cost issues. This dissertation focuses on the novel photovoltaic mechanism for the next generation solar cells using two inorganic nanomaterials, nanocrystal quantum dots and ferroelectric nanoparticles. Lead zirconate titanate (PZT) materials are widely studied and easy to synthesize using solution based chemistry. One of the fascinating properties of the PZT material is a Bulk Photovoltaic effect (BPVE). This property has been spotlighted because it can produce very high open circuit voltage regardless of the electrical bandgap of the materials. However, the poor optical absorption of the PZT materials and the required high temperature to form the ferroelectric crystalline structure have been obstacles to fabricate efficient photovoltaic devices. Colloidal quantum dots also have fascinating optical and electrical properties such as tailored absorption spectrum, capability of the bandgap engineering due to the wide range of material selection and quantum confinement, and very efficient carrier dynamics called multiple exciton generations. In order to utilize these properties, many researchers have put numerous efforts in colloidal quantum dot photovoltaic research and there has been remarkable progress in the past decade. However, several drawbacks are still remaining to achieve highly efficient photovoltaic device. Traps created on the large surface area, low carrier mobility, and lower open circuit voltage while increasing the absorption of the solar spectrum is main issues of the nanocrystal based photovoltaic effect. To address these issues and to take the advantages of the two materials, this dissertation focused on material synthesis for low cost solution process for both materials, fabrication of various device structures and electrical/optical characterization to understand the underlying physics. We successfully demonstrated lead sulfide quantum dots (PbS QDs) and lead zirconate titanate nanoparticles (PZT NPs) in an aqueous solution and fabricated a photosensitive device. Solution based low-temperature process was used to fabricate a PbS QD and a PZT NP device. We exhibited a superior photoresponse and ferroelectric photovoltaic properties with the novel PZT NP device and studied the physics on domain wall effect and internal polarity effect. PZT NP was mainly investigated because PZT NP device is the first report as a photosensitive device with a successful property demonstration, as we know of. PZT's crystalline structure and the size of the nanocrystals were studied using X-ray diffraction and TEM (Transmission electron microscopy) respectively. We observed
Book Synopsis High Efficiency CdTe Ink-Based Solar Cells Using Nanocrystals (Fact Sheet). by :
Download or read book High Efficiency CdTe Ink-Based Solar Cells Using Nanocrystals (Fact Sheet). written by and published by . This book was released on 2015 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt: This NREL Highlight is being developed for the 2015 February Alliance S & T Board meeting and describes a solution-processable ink to produce high-efficiency solar cells using low temperature and simple processing.
Book Synopsis High Efficiency CdTe Ink-Based Solar Cells Using Nanocrystals (Fact Sheet) by :
Download or read book High Efficiency CdTe Ink-Based Solar Cells Using Nanocrystals (Fact Sheet) written by and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This NREL Highlight is being developed for the 2015 February Alliance S and T Board meeting and describes a solution-processable ink to produce high-efficiency solar cells using low temperature and simple processing.
Book Synopsis CuInSe2 Nanocrystal Photovoltaics by : Daniel William Houck
Download or read book CuInSe2 Nanocrystal Photovoltaics written by Daniel William Houck and published by . This book was released on 2019 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanocrystal based photovoltaics (PVs) have the potential to be printed at room temperature on a variety of substrates with the performance and stability required to enable low-cost, lightweight portable power applications. CuInSe2 nanocrystal (PVs), fabricated using methods like those developed for polycrystalline CuIn [subscript x] Ga [subscript 1-x] Se2 (CIGS) PVs, have exhibited some success in this direction, but the efficiency of the devices has been limited. Simulations of CuInSe2 nanocrystal photovoltaic devices using Solar Cell Capacitance Simulator (SCAPS) software indicate that higher performance is not likely to be achieved though ligand exchange procedures that influence the nanocrystals’ electron affinity, as reported for PbS nanocrystal photovoltaics. Higher PV performance requires a combination of increased carrier mobility and longer carrier lifetimes. Both are influenced by the capping ligand chemistry and the presence of defects in the nanocrystals. The nanocrystal synthesis conditions are critical for controlling the defects and phase of the nanocrystal products. X-ray diffraction (XRD) shows that CuInSe2 tends to form the tetragonal chalcopyrite structure while under fast nucleation conditions CuIn [subscript x] Ga [subscript 1-x] Se2 nanocrystals form the hexagonal wurtzite phase. Raman spectroscopy has shown that the CuInSe2 nanocrystals contain a significant concentration of InC [subscript u]+2V [subscript Cu] pair defects that depends on the synthesis conditions. These pair defects tend to order under light excitation and can be eliminated by high temperature annealing. Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy indicates that the oleylamine and diphenylphosphine capping ligands used in a typical CuInSe2 nanocrystal synthesis bind strongly to the nanocrystal surface and exhibit very limited desorption. The addition of I2 induces ligand desorption and facilitates ligand exchange on these nanocrystals. Furthermore, the tightly bound ligands do not evaporate when heated under inert conditions, like the free molecule would. The bound ligands are found to form disordered sp2 carbon that vaporizes over tens of minutes. These studies provide insight for improving the performance of CuInSe2 nanocrystal photovoltaics by showing that the ligand chemistry and defects in CuInSe2 are relatively unique compared to other types of nanocrystals
Book Synopsis Nanostructured Photovoltaic Devices for Next Generation Solar Cell by : Sung Jin Kim
Download or read book Nanostructured Photovoltaic Devices for Next Generation Solar Cell written by Sung Jin Kim and published by . This book was released on 2008 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the search for alternative sources of energy other than petroleum continues to expand, solar energy conversion has already been identified as one of the most promising technologies. In the past few years there has been extensive research focused on the next generation solar cells that can exceed the Shockley-Queisser limit (a model that predicts the maximum achievable efficiency for a given material with a given bandgap). Moreover, nanoengineering approaches to enhance solar power conversion efficiency have started to receive considerable interest. Even in the most efficient commercially available solar devices utilizing crystalline silicon, a major portion of the absorbed ultraviolet photon energy is wasted as heat. Furthermore, this heat is detrimental to device reliability. Colloidal nanocrystal quantum dots (NQDs) offer the exciting prospect of simultaneously manipulating device and material structures and processes to enable more efficient solar energy conversion. Most importantly, these colloidal nanocrystal quantum dots are amenable to inexpensive fabrication techniques such as dip coating or spray coating of the constituent nanoscale materials onto various substrates. This dissertation focuses on the development of nanostructured photovoltaic devices, that exhibit multiple exciton generation, and that exploit the wide absorption spectra enabled by the quantum dots for next generation highly efficient, low cost, solar cells. Firstly, multiple exciton generation and subsequent electrical extraction from a thin film photoconductive device constructed from PbSe NQDs is demonstrated. As an extension of this work, this PbSe NQD photoconductor was used in a tandem structure with a polymer solar cell to demonstrate multiple carrier extraction the application of an external electric field. This structure exhibited improved device durability from UV irradiation due to the self-passivating effect provided by the PbSe layer. In order to achieve better exciton dissociation and charge transport, novel NQDs with functionalized ligands were developed. This research included the development of an approach to produce predefined patterns of quantum dots and multipod nanocrystals. The technique used optical lithography for direct writing of device structures for optoelectronic and electronic devices as well as the ability to change the ligand properties by using heat treatment. CdSe, CdTe, and PbSe nanocrystals were all functionalized by the incorporation of the functional ligand t -butoxycarbonyl (t -BOC). The ability to modify ligands of spin-casted nanocrystal layers by heating enables the fabrication of multi-layered structures. Moreover, the direct photopatterning of nanocrystal device structures was facilitated by the incorporation of a photo acid generator with the t -BOC functionalized nanocrystals. Finally, three different approaches that were recently developed to use t -BOC protected NQDs for photovoltaic devices will be discussed. The three types of devices that were developed include: (1) a multi-layered NQD all inorganic heterojunction photovoltaic devices; (2) a Schottky junction solar cell using a metal electrode on a NQD thin film; and (3) a hybrid (NQD/Polymer) bulk heterojunction device. Detailed characterization of these devices demonstrated that the t -BOC protected NQDs can be used to boost device performance (as compared to devices made from NQD with other ligands). This result provides significant advantages for realizing complicated device structures in the future.
