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Document Type

Thesis - University Access Only

Award Date

2015

Degree Name

Master of Science (MS)

Department

Electrical Engineering and Computer Science

First Advisor

Qiquan Qiao

Abstract

Solar energy is renewable and clean. Silicon based solar cells, which cover 80- 90% of global PV market, are still costly. Dye sensitized solar cells (DSCs) can be low cost alternative to silicon cells as DSCs require low material and fabrication cost. A DSC generally utilizes platinum (Pt) as a counter electrode catalyst material. As Pt is costly and one of the rarest metals, carbonaceous materials such as carbon black, carbon nanotubes and electrospun carbon nanofibers (ECNs) have been investigated as potential low cost replacements for Pt. ECNs have lower production cost than carbon nanotubes and are not detrimental to health, unlike carbon black nanoparticles. The paste of ECNs prepared by mixing them with gel/binders such as polyoxyethylene(12) tridecyl ether (POETE) or (carboxymethyl)-cellulose CMC for doctor blading the ECNs film are reported to have low fill factor (FF), and overall low efficiency. Also, a lot of ECNs are wasted due to their sticking onto the mortar and pestle during the grinding. In this work, spray coated ECNs with titanium dioxide (TiO2) nanoparticles as binder were studied as counter electrodes in DSCs. Spray coating technique helped us to save the amount of ECNs required to make the films by 4-5 times as compared to the grinding and doctor blading technique. Also, the use of TiO2 nanoparticles as binder instead of high resistive insulating binder, CMC, helped to achieve higher FF and overall device efficiency of DSCs. 1:1 wt% ECN:TiO2 composite was found to be the optimum ratio of ECN and TiO2. ECN:TiO2 (1:1) composite counter electrode had higher oxidation-reduction current density and lower charge transfer resistance (RCT) as compared to reference Pt electrode suggesting higher electrocatalytic ability. However, ECN:TiO2 (1:1) composite counter electrode had higher ohmic resistance (RS) than that of reference Pt. The efficiency of 7.25% was achieved using ECN:TiO2 (1:1), as compared to 7.57% of the conventional solution processed Pt based cells. Moreover, the efficiency of ECN:TiO2 (1:1) improved from 7.25% to 7.46% after adding only 8 wt% Pt to the ECN:TiO2 (1:1) composite film, which also demonstrated the potential as cost effective alternative to Pt in DSCs.

Library of Congress Subject Headings

Dye-sensitized solar cells Nanofibers Carbon fibers Electrospinning Electrodes

Description

Includes bibliographical references (pages 55-66)

Format

application/pdf

Number of Pages

78

Publisher

South Dakota State University

Rights

In Copyright - Non-Commercial Use Permitted
http://rightsstatements.org/vocab/InC-NC/1.0/

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