Small-Molecule Semiconductors for High-Efficiency Organic Solar Cells PDF Download

Author: Chuanlang Zhan
Publisher: Frontiers Media SA
ISBN: 2889459802
Category :
Languages : en
Pages : 184

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Author: Mulugeta Ayele Birhanu
Publisher:
ISBN:
Category :
Languages : en
Pages :

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With increasing price of natural gas and petroleum products and their environmental concerns, alternative energy sources are required i.e. renewable energy sources. Solar energy is the abundant form of renewable energy. In addition to that, the total amount of solar power that incident on earth for an hour can cover the world's annual electric power demand. Hence capturing even fraction of this abundant power source is vital. The technologies used to capture solar power are the photovoltaic systems which, through the photovoltaic effect in semiconductors in the solar cells comprising the system; convert the energy in the photons of the sunlight directly to electric power. The system with silicon solar cells has high production cost because of which it has been difficult for the system to be in to grid parity. The best alternative that attracted the attention of many researchers in the world is to use organic solar cells. Unlike their inorganic counterparts; the organic solar cells are easy and cheap to fabricate, light weighted, flexible, the semiconductors are tuneable with respect to their functions, colourful, can absorb light in cloudy days and semitransparent. The amount of semiconductor material required is very small (i.e. in 100nm). Because of these, even with half efficiency of inorganic ones can make them economical. The other advantage is that they can be used in areas where silicon solar cells haven't been used and properties like light weightiness, flexibility and colourfulness are required. This could be in the sports, agriculture, medical sector .... However, they have disadvantages: low efficiency and shorter life span due to degradation of the semiconductors. Some of the factors that determine performance of solar cell are the type of structure used for the active layer of the solar cell and its thickness. The two kinds of structures we used in the lab were the bi-layer and bulk-junction photoactive layer. The performance of the bulk-junction solar cells increase with thickness of the photoactive layer up to certain point due to high intimacy of contact between the donor and acceptor and from this point on wards the performance decreases as recombination starts to dominate the effect of the intimacy of contact. Comparison of the bi-layer and bulk-junction solar cells for certain thickness tells that the bi-layer has higher fill factor and open circuit voltage than the bulk-junction due to relatively low recombination and density of states. The efficiency of organic solar cells is increasing at higher rate recently as researches have been taking place even in big named companies. The degradation of the organic semiconductors is due to oxygen and water valour from air which can be avoided by encapsulation of the solar cells.

Author: Mylène Le Borgne
Publisher:
ISBN:
Category : Oligomers
Languages : en
Pages : 167

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Organic solar cells appear as a promising technology within photovoltaic field owing to their low-cost fabrication and their great flexibility enabling a widespread distribution. For now, they are still at the prototype stage due to their limited efficiency and lifetimes. Many efforts were realized in designing new materials as they are involved in every steps of the photovoltaic process and thus they dictate the cell efficiency. Along this thesis, two series of electron-donating semi-conductors were designed and synthesized. The first series consist in three oligomers containing three diketopyrrolopyrrole units, a well-studied chromophore. Those oligomers absorb up to the near infra-red region, a very interesting feature for light harvesting. Through the engineering of electron-rich spacers, various twists were generated in the oligomers backbone. The oligomer showing a coplanar conformation appears to be the most crystalline and thus exhibits the best charge transport properties with a hole mobility of 10-3 cm2.V-1.s-1. However, bulk heterojunction organic solar cells, this high crystallinity results in an unfavorable morphology and a PCE inferior to 1%. As for the second series, the four small molecules combined 3,3'-(ethane-1,2-diylidene)bis(indolin-2-one) (EBI), an electron deficient unit, and various electron-rich units such as thiophene (EBI-T), benzofuran (EBI-BF) and bithiophene (EBI-2T). Among EBI derivatives, EBI-BF demonstrated the highest hole mobility of 0.021 cm2.V-1.s-1 in field effect transistors due to its coplanar conformation. Meanwhile, in bulk heterojunction solar cells, the highest PCE of 1.92% was obtained with EBI-2T:PC61BM blend owing to a more appropriate morphology and the broadest absorption spectrum of EBI-2T.

Author: Wai-Yeung Wong
Publisher: Springer
ISBN: 3662460548
Category : Technology & Engineering
Languages : en
Pages : 541

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This book presents a critical perspective of the applications of organometallic compounds (including those with metal or metalloid elements) and other related metal complexes as versatile functional materials in the transformation of light into electricity (solar energy conversion) and electricity into light (light generation in light emitting diode), in the reduction of carbon dioxide to useful chemicals, as well as in the safe and efficient production and utilization of hydrogen, which serves as an energy storage medium (i.e. energy carrier). This book focuses on recent research developments in these emerging areas, with an emphasis on fundamental concepts and current applications of functional organometallic complexes and related metal-based molecules for energy research. With contributions from front-line researchers in the field from academia and industry, this timely book provides a valuable contribution to the scientific community in the field of energy science related to metal-based molecular materials. Wai-Yeung Wong, PhD, is Chair Professor and Head of the Department of Chemistry at Hong Kong Baptist University, Hong Kong, P. R. China.

Author: Sam-Shajing Sun
Publisher: CRC Press
ISBN: 1351837060
Category : Technology & Engineering
Languages : en
Pages : 916

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Recently developed organic photovoltaics (OPVs) show distinct advantages over their inorganic counterparts due to their lighter weight, flexible shape, versatile materials synthesis and device fabrication schemes, and low cost in large-scale industrial production. Although many books currently exist on general concepts of PV and inorganic PV materials and devices, few are available that offer a comprehensive overview of recently fast developing organic and polymeric PV materials and devices. Organic Photovoltaics: Mechanisms, Materials, and Devices fills this gap. The book provides an international perspective on the latest research in this rapidly expanding field with contributions from top experts around the world. It presents a unified approach comprising three sections: General Overviews; Mechanisms and Modeling; and Materials and Devices. Discussions include sunlight capture, exciton diffusion and dissociation, interface properties, charge recombination and migration, and a variety of currently developing OPV materials/devices. The book also includes two forewords: one by Nobel Laureate Dr. Alan J. Heeger, and the other by Drs. Aloysius Hepp and Sheila Bailey of NASA Glenn Research Center. Organic Photovoltaics equips students, researchers, and engineers with knowledge of the mechanisms, materials, devices, and applications of OPVs necessary to develop cheaper, lighter, and cleaner renewable energy throughout the coming decades.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Haining Tian
Publisher: Springer
ISBN: 9811059241
Category : Technology & Engineering
Languages : en
Pages : 539

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This book shows the different molecular devices used for solar energy conversion and storage and the important characterization techniques for this kind of device. It has five chapters describing representative molecule-based solar cells, such as organic solar cells, dye-sensitized solar cells and hybrid solar cells (perovskite solar cell and quantum dots solar cells). It also includes two chapters demonstrating the use of molecular devices in the areas of solar fuel, water splitting and carbon dioxide reduction. There are further two chapters with interesting examples of solar energy storage related devices, like solar flow battery, solar capacitor and solar energy-thermal energy storage. Three chapters introduce important techniques used to characterize, investigate and evaluate the mechanism of molecular devices. The final chapter discusses the stability of perovskite solar cells. This book is relevant for a wide readership, and is particularly useful for students, researchers and industrial professionals who are working on molecular devices for solar energy utilization.

Author: Guanying Chen
Publisher: MDPI
ISBN: 303842532X
Category : Science
Languages : en
Pages : 187

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This book is a printed edition of the Special Issue "Nanostructured Solar Cells" that was published in Nanomaterials

Author: Yongfang Li
Publisher: Springer
ISBN: 3319168622
Category : Technology & Engineering
Languages : en
Pages : 402

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This volume reviews the latest trends in organic optoelectronic materials. Each comprehensive chapter allows graduate students and newcomers to the field to grasp the basics, whilst also ensuring that they have the most up-to-date overview of the latest research. Topics include: organic conductors and semiconductors; conducting polymers and conjugated polymer semiconductors, as well as their applications in organic field-effect-transistors; organic light-emitting diodes; and organic photovoltaics and transparent conducting electrodes. The molecular structures, synthesis methods, physicochemical and optoelectronic properties of the organic optoelectronic materials are also introduced and described in detail. The authors also elucidate the structures and working mechanisms of organic optoelectronic devices and outline fundamental scientific problems and future research directions. This volume is invaluable to all those interested in organic optoelectronic materials.

Author: Ismail Alperen Ayhan
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Renewable energies significantly gained in importance in the last decade. Due to worldwide ecological problems and global warming, much effort is needed to increase the awareness and protect earth from the impacts with respect to the climate changes. Particularly, the excessive use of fossil fuels force countries to figure out some alternative applications for the energy supply. Other than hydro and wind-based applications, solar energy becomes the most important renewable technology to reduce the carbon dioxide emission and worldwide photovoltaic systems have recently been installed by gradually rising. Since only China and India are building several coal powers every week for energy needs based-on their population1, it is very important to develop efficient and low-cost solar energy systems to attract attention for especially newly develop countries other than develop ones. Organic solar cells (OSCs) are one of the most promising solar energy systems due to some unique advantages, such as low-cost, lightweight, flexible, semitransparent, large area compatibility, easy fabrication (roll to roll), easy processing (from solution), and energy level tunability, which enables new fields of applications. In contrast to inorganic solar cells, high temperature fabrication techniques are not needed to prepare organic photovoltaics. In solution processed OSCs, the organic semiconductor materials are used in active layer to absorb light and convert it to electrical energy. The active layers containing donor and accepter components where the optimized morphology is achieved through an interpenetrating phase-separated donor-acceptor network that is called as bulk heterojunction. The efficiency of bulk heterojunction OSCs is strongly correlated with the morphology of their active layers, which requires an optimized distribution of the donor and acceptor domains. A large interface between donor and acceptor domains are needed to obtain efficient exciton dissociation at interface. Also, percolation pathways are required to transport the charges to the corresponding electrodes. The nanomorphology depends on tendency of the active layer components to crystallization and phase-separation. These morphological properties can be optimized by altering the process parameters, such as selection of materials and solvents, composition, thickness, and thermal treatments. Recently, OSCs has been remarkably enhanced with power conversion efficiency exceeding 16% by virtue of new materials development and device optimizations.2--4 It is commonly known that the limited absorption window of organic semiconductors causes low photon-harvesting ability from active layer. Multi-component organic solar cells, which consist of one donor and two acceptors, are a promising strategy for broadening the light absorption spectrum and enhancing the power conversion efficiency (PCE) of the organic photovoltaic devices, due to the diverse small molecular materials with different optical band gaps and good compatibility. In this dissertation, the binary and ternary blend systems were studied through optimizing processing parameters and the effect of these parameters on the structural, morphological, electrical and photovoltaic properties were investigated by performing UV-vis absorption, EQE measurement, Grazing-Incidence Wide-Angle X-ray Scattering (GIWAXS) and energy-filtered transmission electron microscopy (EFTEM). In the first part of dissertation, it is found that optimized blends share a universal fibril-like structure, where the polymer donor appears to dictate fibril size. In the second part of section, the effect of third component in ternary blend OSCs is discussed where the optimum morphology is achieved and if the ternary blend systems also have similar morphology such as fibril-like structure. As expected, the ternary blend system showed significant enhancement of device performance due to broadening of the absorption spectrum and the fill factor. We attribute that the high morphology compatibility of the ternary system can benefit to optimized electron/hole mobility and diminished recombination.