Master of Science (MS)
Semester of Degree Completion
Dyes-sensitized solar cells (DSCs) are of importance to efficient conversion of solar energy to electricity. The modern version of a DSC is a titanium dioxide nanoparticles-based electrochemical device, in which solar energy is absorbed by dye molecules and electrons from excited dye molecules are injected into the conduction band of titanium dioxide nanoparticle. The electrons are then transported through a network of interconnected TiO2 particles to the fluorine- tin -oxide layer to the external circuit. In this process dye molecules are crucial to the device's energy conversion efficiency.
Boron-dipyrromethenes, known as BODIPY dyes, show strong absorption in the visible light region. They have high fluorescence quantum yields and are soluble in most organic solvents. They also exhibit strong photostability making them suitable for DSC applications. The meso-substituted BODIPY dyes showed poor photovoltaic performance. However, several studies have shown the promise of 2- or 6-position substituted BODIPY dyes for DSCs.
Two BODIPY dyes, HHK1 and HHK2, with a premium donor-π-acceptor molecular configuration were successfully synthesized using Sonogashira coupling reactions. The yields were with 90 % yield for HHK1 and the yield for HHK2 was not determined. Two dyes were also characterized by NMR, MS, UV-Vis spectrum, and fluorescence spectroscopy. The absorption peak for HHK1 was red shifted from 503 nm in PB without any substituent in 2 and 6 positions to 575 nm. For HHK2 dye the absorption was red shifted to 576 nm due to the bulky hexyloxy group on the aldehyde. This hexyloxy group on the benzene group in the meso position. Fluorescence spectra showed emission peaks at 592 nm and 670 nm for HHK1 and HHK2, respectively. The absorption spectra of HHK1 and HHK2 on TiO2 film were blue shifted and the peaks became narrower.
The photovoltaic performance of HHK1 and HHK2 sensitized solar cells exhibited efficiency of 0.87% and 0.57%, respectively.
Klfout, Hafsah, "Novel BODIPY Dyes for Dye-sensitized Solar Cells" (2015). Masters Theses. 2377.