Improvement of Power Conversion Efficiency in Dye Sensitized Solar Cells (DSSCs)

Abstract

Dye-sensitized solar cells (DSSCs) have attracted considerable attention in recent years as they offer the possibility of low-cost conversion of photovoltaic energy. Typical structure of DSSC consists of conduction glass substrate (FTO of ITO), wide-band gap semiconductor (TiO2), sensitizers, electrolyte, and Pt counter electrode. In this thesis, the useful methods for elevating an efficiency of DSSCs, such as an anti-refraction coating at the front glass (chapter 3), a blocking layer for prevention of the recombination between the TiO2 electrode and the electrolyte (chapter 4), and the low temperature sintering in DSSCs (chapter 5) are discussed. Chapter 2 introduces materials, mechanism, and structure of DSSCs. Operation principle of DSSCs was reviewed in details. Recent studies on metal oxide electrodes, dyes and electrolytes were introduced. In chapter 3, a simple low temperature-method of preparing single-layer AR films for elevating efficiency of DSSCs was presented. Single-layered porous silica films were prepared on pholyethylene thetephthalate (PET) substrates as antireflection coatings for efficient, flexible optoelectronic devices, Cetyltrimethylammonium bromide (CTAB)-templated synthesis was employed to form porous silica films. Without using high temperature treatment, CTAB was removed by washing in water to create a porous structure in the films. The average reflectance of as-prepared AR coatings on PET substrate was =< 2%. In chapter 4, phenyltrimethoxysilane (PTMS) as an insulating molecular layer in order to prevent the recombination process was presented. PTMS was used to prevent interfacial recombination between TiO2 electrode and electrolyte after dye loading. PTMS treatment of TiO2 nanoparticles in dye-sensitized solar cells noticeably improved the overall conversion efficiency owing to the increase in the short circuit current density. A conversion efficiency of 8.6% was achieved, which corresponds to a 10.3 % enhancement over that of the reference cell. In chapter 5, DSSCs using ZnO photoelectrode sintered at low temperature and surface coating for enhanced connection between ZnO particles were presentated. ZnAc2 &#8729

2H2O solution was employed to enhance connection between ZnO particles, and its influence on the DSSCs using ZnO photoelectrode sintered at low-temperature. It was confirmed that cell efficiency was increased. Pt catalysis was activated without heat treatment after Pt was coated on the substrate by e-beam evaporation.