염료감응형 태양전지의 상대 전극으로써 CNT/PEDOT Core/Shell 나노구조체의 제조 = Preparation of CNT/PEDOT Core/Shell nanostructures as a counter electrode in dye-sensitized solar cells

다국어 초록 (Multilingual Abstract)

Multi-wall carbon nanotubes (MWCNTs)-core/thiophene polymer-shell nanostructure was synthesized by chemical oxidative polymerization of 3,4-ethylenedioxy thiophene (EDOT) with oxidant (FeCl3) using a surfactant, dodecylbenzene sulfonic acid (DBSA). Upon the addition of EDOT and oxidant, the polymerization takes place on the surface of the CNTs and poly(3,4-ethylenedioxy thiophene) (PEDOT) is gradually deposited on the surface of the CNTs. To confirm the structures and properties of the nanostructure, it was characterized by Fourier transform-infrared spectroscopy (FT-IR), x-ray diffraction (XRD), field emission-transmission electron microscopy (FE-TEM), high resolution-transmission electron microscopy (HR-TEM) and thermogravimetric analysis (TGA), respectively. The nanostructure showed PEDOT-coated CNT structure and the thickness of PEDOT layers was 2-5 nm. Addition of the CNTs enhanced the rate of polymerization and thermal property, and electrical conductivity of PEDOT-coated CNT increased.
To investigate the applications for the counter electrode in dye-sensitized solar cells (DSSCs), synthesized PEDOT-coated CNT was measured by current density-voltage measurement, incident photon-to-current conversion efficiency (IPCE) and electrochemical impedance spectroscopy (EIS). Open-circuit voltage (VOC), fill factor (FF) and conversion efficiency (η) of PEDOT-coated CNT were improved compared to those of the CNT and PEDOT. Besides, it was verified that PEDOT-coated CNT has advantages to prevent the backward reactions such as dark current and recombination. Consequently, it can be explained by the fact that these types of nanostructures are efficient materials as the counter electrode for DSSCs.

목차 (Table of Contents)

• CONTENTS
• 국 문 요 지 ………………………………………………… iii
• List of Scheme ……………………………………………… iv
• List of Figures ………………………………………………… v
• List of Tables ……………………………………………… vii
• 1. Introduction ……………………………………………… 1
• 2. Experimental ……………………………………………… 4
• 2.1 Fabrication of CNT/PEDOT core/shell nanostructures ……………………………………… 4
• 2.2 Electrode preparation and Cell configuration
• ………………………………………………………… 4
• 2.3 Characterization ……………………………… 6
• 3. Results and discussion …………………………………10
• 3.1 Characteristics of CNT/PEDOT core/shell nanostructures ……………………………………… 10
• 3.1.1 TEM image ……………………………………… 10
• 3.1.2 FT-IR spectra …………………………………… 12
• 3.1.3 WAXD patterns ………………………..………… 14
• 3.1.4 Polymerization yield and electrical conductivity
• ……….………………………………………… 16
• 3.1.5 TGA thermograms ……………………………… 18
• 3.2 DSSC performance …………………………………… 21
• 3.2.1 J-V curves and IPCE spectra ………………… 21
• 3.2.2 EIS …………………………..…………………… 26
• 4. Conclusions ……………………………………………… 31
• 5. References ………………………………………………… 32
• ABSTRACT ………………………………………………… 35