Beaumont, Nicola L. (2013) Investigating new materials and understanding the ambipolar qualities of organic small molecules for use in organic photovoltaics. PhD thesis, University of Warwick.

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Abstract

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.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QC Physics Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Photovoltaic cells, Organic semiconductors
Official Date:	May 2013
Dates:	Date Event May 2013 Submitted
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Jones, T. S. (Tim S.); Hatton, Ross
Extent:	xv, 182 leaves : illustrations, charts.
Language:	eng

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