Small Molecules Based on Novel Electron-deficient Acceptor Units for Organic Electronic Applications PDF Download

Author: Joseph Cameron
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Languages : en
Pages : 446

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Book Description
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.