Date of Award

6-2013

Degree Name

Doctor of Philosophy

Department

Physics

First Advisor

Dr. Clement Burns

Second Advisor

Dr. Paul Pancella

Third Advisor

Dr. Guda Ramakrishna

Fourth Advisor

Dr. Asghar Kayani

Keywords

high dielectric constant materials, copper phthalocyanine, organic solar cells, CuPc, polarization mechanisms

Abstract

The efficiency of organic solar cells still lags behind inorganic solar cells due to their low dielectric constant which results in a weakly screened columbic attraction between the photogenerated electron-hole system, therefore the probability of charge separating is low. Having an organic material with a high dielectric constant could be the solution to get separated charges or at least weakly bounded electron-hole pairs. Therefore, high dielectric constant materials have been investigated and studied by measuring modified metal-phthalocyanine (MePc) and polyaniline in pellets and thin films. The dielectric constant was investigated as a function of temperature and frequency in the range of 20Hz to1MHz. For MePc we found that the high dielectric constant was an extrinsic property due to water absorption and the formation of hydronuim ion allowed by the ionization of the functional groups such as sulphonated and carboxylic groups. The dielectric constant was high at low frequencies and decreasing as the frequency increase. Investigated materials were applied in fabricated bilayer heterojunction organic solar cells. The application of these materials in an organic solar cells show a significant stability under room conditions rather than improvement in their efficiency.

Access Setting

Dissertation-Open Access

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