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Title: Investigating new materials and understanding the ambipolar qualities of organic small molecules for use in organic photovoltaics
Author: Beaumont, Nicola L.
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2013
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Organic photovoltaics (OPVs) have huge potential for competing with current inorganic photovoltaics in the search for a reliable, renewable source of energy. It is thought that only ~10 % efficiency is necessary for commercialisation and also allows avenues towards flexible, compact, lightweight optoelectronics, with current certified efficiencies already at 12%! Although the current efficiencies have surpassed expectations in order to continue the high progress new materials need to be investigated. Through understanding current materials and utilising new donor and acceptor materials the hopes of achieving higher efficiencies are realistic. Halogenation as a method to modify current organic semiconductors materials has successfully been demonstrated with minimal change to the optical properties. Successful modification of copper phthalocyanines (CuPc) to the fluorinated F16 CuPc derivative resulted in a large change in ionisation potential allowing for its use as an acceptor. This thesis will discuss the modification of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPSEpent) via chlorination in the hopes of achieving a more efficient donor material in single heterojunction devices. Through addition of electron withdrawing groups, the molecular frontier orbitals can be tuned to allow for improved stability towards C60 in solution, larger ionisation potentials which allow for larger interface gaps when used in devices, resulting in improvements in open circuit voltage (Voc), short circuit current (Jsc) and power conversion efficiency. The second part of the thesis will concentrate on the ambipolar qualities of (sub)phthalocyanines and their use as acceptors in conjunction with both the underused acene, tetracene (Chapter 5) and the more widely studied pentacene (Chapter 6). To obtain a strong understanding of using boron subphthalocyanine chloride (SubPc), Cl6-SubPc and ClAlPc as acceptors, UV –Vis absorption, atomic force microscopy (AFM), photoluminescence (PL), photoelectron spectroscopy (PES), space charge limited current (SCLC) theory to gain charge mobilities and devices were explored.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QC Physics ; QD Chemistry