Investigating New Materials and Understanding the Ambipolar Qualities of Organic Small Molecules for Use in Organic Photovoltaics PDF Download
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Author: Nicola L. Beaumont
Publisher:
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Category :
Languages : en
Pages : 0
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Author: Nicola L. Beaumont
Publisher:
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Category :
Languages : en
Pages : 0
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Author: Liming Ding
Publisher: John Wiley & Sons
ISBN: 3527833668
Category : Technology & Engineering
Languages : en
Pages : 988
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Book Description
Organic Solar Cells A timely and singular resource on the latest advances in organic photovoltaics Organic photovoltaics are gaining widespread attention due to their solution processability, tunable electronic properties, low temperature manufacture, and cheap and light materials. Their wide range of potential applications may result in significant near-term commercialization of the technology. In Organic Solar Cells: Materials Design, Technology and Commercialization, renowned scientist Dr. Liming Ding delivers a comprehensive exploration of organic solar cells, including discussions of their key materials, mechanisms, molecular designs, stability features, and applications. The book presents the most state-of-the-art developments in the field alongside fulsome treatments of the commercialization potential of various organic solar cell technologies. The author also provides: Thorough introductions to fullerene acceptors, polymer donors, and non-fullerene small molecule acceptors Comprehensive explorations of p-type molecular photovoltaic materials and polymer-polymer solar cell materials, devices, and stability Practical discussions of electron donating ladder-type heteroacenes for photovoltaic applications In-depth examinations of chlorinated organic and single-component organic solar cells, as well as the morphological characterization and manipulation of organic solar cells Perfect for materials scientists, organic and solid-state chemists, and solid-state physicists, Organic Solar Cells: Materials Design, Technology and Commercialization will also earn a place in the libraries of surface chemists and physicists and electrical engineers.
Author: Ye Zhou
Publisher: Royal Society of Chemistry
ISBN: 1788019288
Category : Technology & Engineering
Languages : en
Pages : 463
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Book Description
Ambipolar materials represent a class of materials where positive and negative charge carriers can both transport concurrently. In recent years, a diverse range of materials have been synthesized and utilized for implementing ambipolar charge transport, with applications in high‐density data storage, field effect transistors, nanotransitors, photonic memory, biomaterial-based memories and artificial synapses. This book highlights recent development of ambipolar materials involving materials design, fundamental principles, interface modifications, device structures, ambipolar characteristics and promising applications. Challenges and prospects for investigating ambipolar materials in electronics and optoelectronics are also discussed. With contributions from global leaders in the field, this title will appeal to graduate students and researchers who want to understand the design, materials characteristics, device operation principles, specialized device application and mechanisms of the latest ambipolar materials.
Author: Jessica D. Douglas
Publisher:
ISBN:
Category :
Languages : en
Pages : 188
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The chemical structure of conjugated semiconducting materials strongly influences the performance of organic photovoltaic (OPV) devices. Thus a good understanding of the structure-function relationships that govern the optoelectronic and physical properties of OPV materials is necessary. In this dissertation, organic polymers and small molecules are evaluated in terms of OPV device output parameters, and molecular design rules are elucidated. The development of molecules with alternating electron-rich and electron-deficient backbone units provides materials with suitable optoelectronic properties for OPVs and favorable modularity for organic semiconductor design. The choice of specific aromatic units and side chains for conjugated materials are shown to modulate the energy levels and architecture of OPV devices, affecting each of the four mechanistic steps of OPV operation. In Chapter 2, the relationship between molecular packing parameters and the bulkiness of aliphatic solubilizing group extending away from a polymer backbone is elucidated, and high-performance OPV devices are achieved. In Chapter 3, the inclusion of a post-processing functionality on a polymer side chain is found to have a positive effect on the bulk morphology and overall performance of OPV devices. In Chapter 4, the influence of electron-withdrawing and quinoidal monomers on the optoelectronic properties of conjugated polymers is established, and energy level modulation is shown to affect the electron accepting and donating capabilities of OPV materials in a blended device. In Chapter 5, small molecules are designed with complementary light absorption properties in order to investigate a rarely observed charge generation mechanism.
Author: Ye Zhou
Publisher: Royal Society of Chemistry
ISBN: 1788018680
Category : Technology & Engineering
Languages : en
Pages : 463
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Book Description
This book highlights recent development of ambipolar materials involving materials design, fundamental principles, interface modifications, device structures, characteristics and promising applications.
Author: David Fraser Zeigler
Publisher:
ISBN:
Category :
Languages : en
Pages : 168
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Author: Joseph Cameron
Publisher:
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Category :
Languages : en
Pages : 0
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Demand for photovoltaic cells is ever-increasing due to the diminishing supply of oil-based fuels and the associated harmful environmental effects. Organic photovoltaic devices offer a light and flexible alternative to Si-based PVs. In addition to this, they can be processed using fabrication methods such as spin-coating and inkjet printing hence, such devices have potential to be produced cheaply on a large scale. Although they have been applied as donor materials with success, polymers often show end-group variation and are polydisperse so there can be batch-to-batch variation with respect to OPV performance. A solution to these problems is the use of small donor molecules which are monodisperse and have well-defined structures. However, the shorter conjugation of small molecules with respect to polymers requires measures to shorten the HOMO-LUMO gap. A common approach is the incorporation of electron-deficient acceptor units into the donor molecule, lowering the LUMO level and therefore the HOMO-LUMO gap.Chapter 1 reviews band theory, the development of organic semiconductors, including a summary of oligothiophene based materials and common electron-deficient acceptor units used, the principles behind OPV and OFET devices and how organic semiconductors can be optimised in order to produce the best working devices.The synthesis, physical properties and OPV performance of materials based on naphthyridine-2,6-dione acceptor unit are presented in chapter 2, focussing on the difference between compounds with Donor-Acceptor-Donor and Acceptor-Donor-Acceptor structures. Chapter 3 shows the novel naphthyridin-2-one moiety and the synthesis of materials containing the unit and how they have been used for different applications including ambipolar OFETs and both donor and acceptor materials for bulk heterojunction OPV devices.A study in improving the mobility of OFET devices is presented in chapter 4. Different inorganic nanoparticles were added to organic semiconductor solutions for and the effect of this simple process on the performance of the OFET devices is discussed.Chapter 5 introduces the thieno[3,2-b]thiophene-2,5-dione and novel furo[3,2-b]furan-2,5-dione acceptor units. The synthesis, optical and electrochemical properties, and OFET and OPV device optimisation of materials based on these moieties are presented and discussed.A summary of the work discussed is presented in chapter 6 whilst chapter 7 presents the experimental methods for electrochemistry, device work, and synthetic procedures for each compound presented in Chapters 2, 3, 4 and 5.
Author: Chunxiang Chen
Publisher:
ISBN:
Category :
Languages : en
Pages : 225
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Book Description
Organic solar cells appear as a promising technology to meet future energy requirements, owing to their low production costs, their great flexibility and their ability to be integrated into light devices. Currently, they exhibit modest performances in photoconversion, thus new active molecules with optimized structural properties need to be developed. This work comes in that aim: on the basis of theoretical calculations with density functional theory, new organic semiconductors have been designed and synthesized. For this, the more economical and cleaner syntheses techniques have been employed. Thus, the coupling of the benzothiadiazole with thiophene carboxhaldehyde via direct heteroarylation without additive nor ligand is performed with success for the first time. According to green chemistry techniques, five molecules are thus isolated in only two steps. The study of their optical and electronic properties by means of different spectroscopic techniques (UV/vis, fluorescence) and electrochemistry, of their thermal properties, and of their ability to self-organize have revealed their promising abilities for use in organic photovoltaics. A series of small molecules based on dithienosilole (DTS) core have also been designed via DFT computations. The calculations show their considerable low bandgap. Their syntheses have been conducted. It anticipates their promising potential for organic photovoltaic applications. Finally, a purely theoretical work has been completed on molecules derived from boron subphthalocyanines. The calculations predict interesting electronic properties for these new materials that may lead to promising performances in organic photovoltaics, paving the way for innovative materials.
Author: Chuanfei Wang
Publisher: Linköping University Electronic Press
ISBN: 9176853934
Category :
Languages : en
Pages : 84
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Book Description
The great tunability of structure and electronic properties of ?-conjugated organic molecules/polymers combined with other advantages such as light weight and flexibility etc., have made organic-based electronics the focus of an exciting still-growing field of physics and chemistry for more than half a century. The application of organic electronics has led to the appearance of wide range of organic electronic devices mainly including organic light emitting diodes (OLED), organic field effect transistors (OFET) and organic solar cells (OSC). The application of the organic electronic devices mainly is limited by two dominant parameters, i.e., their performance and stability. Up to date, OLED has been successfully commercialized in the market while the OSC are still on the way to commercialization hindered by low efficiency and inferior stability. Understanding the energy levels of organic materials and energy level alignment of the devices is crucial to control the efficiency and stability of the OSC. In this thesis, energy levels measured by different methods are studied to explore their relationship with device properties, and the strategies on how to design efficient and stable OSC based on energy level diagrams are provided. Cyclic Voltammetry (CV) is a traditional and widely used method to probe the energy levels of organic materials, although there is little consensus on how to relate the oxidation/reduction potential ((Eox/Ered) to the vacuum level. Ultraviolet Photoelectron Spectroscopy (UPS) can be used to directly detect vertical ionization potential (IP) of organic materials. In this thesis, a linear relationship of IP and Eox was found, with a slope equal to unity. The relationship provides for easy conversion of values obtained by the two techniques, enabling complementarily use in designing and fabricating efficient and stable OSC. A popular rule of thumb is that the offset between the LUMO levels of donor and acceptor should be 0.3 eV, according to which a binary solar cell with the minimum voltage losses around 0.49 V was designed here. Introduction of the ternary blend as active layer is an efficient way to improve both efficiency and stability of the OSC. Based on our studied energy-level diagram within the integer charge transfer (ICT) model, we designed ternary solar cells with enhanced open circuit voltage for the first time and improved thermal stability compared to reference binary ones. The ternary solar cell with minimum voltage losses was developed by combining two donor materials with same ionization potential and positive ICT energy while featuring complementary optical absorption. Furthermore, the fullerene acceptor was chosen so that the energy of the positive ICT state of the two donor polymers is equal to the energy of negative ICT state of the fullerene, which can enhance dissociation of all polymer donor and fullerene acceptor excitons and suppress bimolecular and trap-assistant recombination. Rapid development of non-fullerene acceptors in the last two years affords more recipes of designing both efficient and stabile OSC. We show in this thesis how non-fullerene acceptors successfully can be used to design ternary solar cells with both enhanced efficiency and thermal stability. Besides improving the efficiency of the devices, understanding of the stability and degradation mechanism is another key issue. The degradation of conjugated molecules/polymers often follow many complicated pathways and at the same time many factors for degradation are coupled with each other. Therefore, the degradation of non-fullerene acceptors was investigated in darkness by photoelectron spectroscopy in this thesis with the in-situ method of controlling exposure of O2 and water vapor separately.
Author: Janice Lin
Publisher:
ISBN:
Category :
Languages : en
Pages : 179
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Book Description
The sun produces 1020 W m-2 of energy per day; that is, in one hour, the earth receives enough energy to power the earth for an entire year. This energy can be harvested for a range of processes, including water splitting, photocatalysis, and electricity. Photovoltaic technologies, in particular, harness the energy of the sun to produce electrical energy. Organic solar cells, or organic photovoltaics (OPVs), hold advantages over inorganic cells in scalability, range of functionalization, and potential in flexible applications. While the power conversion efficiency (PCE) of this relatively new type of solar cell has made tremendous progress over the last decade, OPVs must continue to improve over 15% PCE in order to become a viable competitor to inorganic cells. Several factors in the active layer (donor and acceptor layers) of a solar cell can lead to low efficiency, including low carrier mobility, inadequate absorption of the electromagnetic spectrum, and disordered morphology. Therefore, control of morphology in the active layer and tuning of electronic levels of the donors and acceptors in organic photovoltaics are important parameters that need to be controlled for favorable device performance. One approach to improving efficiency is designing molecules that pack closely together to allow for efficient charge transport. These types of systems offer significant possibilities for controlled morphologies, high charge transport, and high efficiencies in solar cells. Towards these types of materials, this work aims to: 1. Understand the effect of torsional behavior in organic materials on the morphology of the active layer to guide the design of materials with low disorder. 2. Determine the effect of crystal packing on charge transport of organic small-molecules and oligomers to lend insight into mechanisms that govern high mobility, and 3. Characterize optical properties of trimeric oligomers to lend insight into potential electronic applications. Motivated by the potential of new organic photovoltaic materials, this thesis begins with a focus on using computational methods to understand systems of relevance to organic electronics (Chapters 1-7). Early projects aim to use an iterative computational-experimental scheme to understand morphology and charge transport as relevant in organic electronic devices (Chapters 1-3). Molecular properties are calculated and correlated to bulk properties observed experimentally to derive design principles for new molecules that would give rise to interesting packing in solid state. Excited state calculations are used to understand the underlying properties that give rise to optical transitions and to predict new molecules that would absorb strongly in the visible light region (Chapters 4). Mechanistic studies of the degradation pathways of small molecules will also be discussed, and functional handles that would lead to more stable structures are identified (Chapter 5). Calculations are employed to understand the transformation of polydiacetylene polymers to graphene nanoribbons, which lends insight into tuning this reaction for other N-doped materials (Chapter 6). Later in the thesis, the focus diverges to the use of computations to understand the reactivity of a class of ruthenium-based olefin metathesis catalysts towards the design of a stable, E-selective catalyst (Chapter 7-8). Various methods are employed in the chapters described in this dissertation. Density functional theory is used to characterize ground state geometry, conformational analysis, transition state geometry, molecular orbitals, reorganization energies. Time-dependent density functional theory is used to characterize excited state properties, including bandgap, absorption, emission, excited state geometry, charge transfer properties. ZINDO is used for other excited state properties such as charge transfer, electronic coupling. Molecular dynamics is used for time-scale properties, including electronic disorder, energetic disorder, ordered and disordered morphology. Kinetic Monte Carlo as implemented in the VOTCA program is used for charge transport calculations.
