Defense Date

2013

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Engineering

First Advisor

James Jr McLeskey

Abstract

This dissertation reports the fabrication and characterization of thin films from the water soluble polymer sodium poly[2-(3-thienyl)-ethyloxy-4-butylsulfonate] (PTEBS) by electrospray deposition (ESD). Contiguous thin films were created by adjusting the parameters of the electrospray apparatus and solution properties to maintain a steady Taylor cone for uniform nanoparticle aerosolization and controlling the particle water content to enable coalescence with previously deposited particles. The majority of deposited particles had diameters less than 52 nm. A thin film of 64.7 nm with a root mean square surface roughness of 20.2 nm was achieved after 40 minutes of ESD. Hybrid Solar Cells (HSCs) with PTEBS thin films from spin coating and electrospray deposition (ESD) were fabricated, tested, and modeled. A single device structure of FTO/TiO2/PTEBS/Au was used to study the effects of ESD of the PTEBS layer on device performance. ESD was found to double the short circuit current density (Jsc) by a factor of 2 while decreasing the open circuit voltage (Voc) by half compared to spin coated PTEBS films. Comparable efficiencies of 0.009% were achieved from both device construction types. Current-Voltage curves were modeled using the characteristic solar cell equation showed a similar increase in generated photocurrent with a decrease of two orders of magnitude in the saturation current in devices from ESD films. Increases in Jsc are attributed to increased interfacial contact area between the TiO2 and PTEBS layers, while decreases in Voc are from poor film quality from ESD. Polymer solar cells (PSCs) with water-soluble active layers deposited by ESD were fabricated and tested. The water soluble, bulk heterojunction active layers consisted of PTEBS and the fullerene C60 pyrrolidine tris-acid. A single device structure of ITO/PEDOT:PSS/bulk(PTEBS+C60)/Al was used to study the effect of PTEBS to C60 tris-acid ratio on photovoltaic performance. An active layer ratio of PTEBS:C60 tris-acid (1:2) achieved the highest power conversion efficiency (0.0022%), fill factor (0.25), and open circuit voltage (0.56 V). The percolation threshold of C60 was achieved between 1 part PTEBS and 2 to 3 parts C60. Increasing the C60 tris-acid ratio (1:3) improved short circuit current, but reduced the open circuit voltage enough to lower efficiency.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

August 2013

Included in

Engineering Commons

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