Date of Award

Summer 2013

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical & Computer Engineering

Program/Concentration

Electrical and Computer Engineering

Committee Director

Gon Namkoong

Committee Member

Helmut Baumgart

Committee Member

Sylvain Marsillac

Call Number for Print

Special Collections LD4331.E55 S2555 2013

Abstract

Organic solar cells (OSCs) are a promising alternative to conventional silicon solar cells. These organic devices offer the promise of facile low cost large scale solution based processing on lightweight, flexible, plastic substrates. At the present state of the technology, however, OSCs exhibit relatively low power conversion efficiencies. To improve these efficiencies, new materials are constantly being developed.

One such material is the fullerene indene-C60 bisadduct (ICBA). When implemented in a poly(3-hexylthiophene-2, 5-diyl) (P3HT) : ICBA bulk heterojunction solar cell, these devices exhibit open circuit voltages exceeding 0.8 V, a value much higher than the devices made implementing phenyl-C61-butyric acid methyl ester (PCBM) which exhibit open circuit voltages of about 0.6 V. This increase in open circuit voltage (Voc) leads to an increase in device efficiency. However, ICBA experiences solubility problems in common organic solvents; thus, special care must be taken in the preparation of P3HT:ICBA photoactive solution. This thesis explores several preparation techniques including sonication, adding solvent additives, stirring and sonicating separately, and mixed solvents.

Solar cells were fabricated using seven P3HT:ICBA solutions prepared differently. Current density-voltage (JV) measurements were done to characterize photovoltaic performance. Fitting was done to extract diode parameters for more in depth electrical characterization. Atomic force microscopy (AFM), HIROX imaging, and X-ray diffraction (XRD) measurements were done to determine physical properties of the cast thin films. Ultraviolet-visible (UV-Vis) absorption spectroscopy was done to observe optical properties of the solar cells. It was found that sonicating the P3HT:ICBA solution prior to stirring produced the most efficient device due to superior electrical, physical, and optical properties while further improvements were found after using the solvent additive octanedithiol (ODT).

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DOI

10.25777/b2r9-3m06

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