Understanding the design principles of organic sensitizers for highly efficient dye sensitized solar cells

Abstract

The conversion of solar to electrical power has presented itself as a solution to meet the growing energy demand and replace our current fossil fuel dependence, which causes dramatic damages to the environment. At the heart of this challenge lies the performance optimization of photovoltaic (PV) technologies, but also rendering their manufacture cost-effective. Dye sensitized solar cells (DSSCs) have attracted significant attention over the past decades because of their low-cost, facile manufacturing processes and wide range of very peculiar applications. Notably, DSSCs can power portable electronic devices under low ambient light or be used as semi-transparent cells for building integrated photovoltaics(BIPV). These attractive features are the consequence of the device’s unique architecture. A layer of mesoporous titanium dioxide (TiO2) is coated with a colored light absorber in contact with a redox active electrolyte, squeezed between a counter electrode.

Dye design is an important step in developing high efficiency devices as each of the dye structural feature will influence its opto-electrochemical properties. Modern era dyes are constructed according to the Donor-π-Acceptor(D-π-A) pattern, where the donor would be an electron rich moiety and the acceptor an electron poor one. The D-π-A pattern was improved over the years, by adding an auxiliary electron accepting unit between the donor and the π-bridge to yield the new D-A-π-A pattern.

The aim of this thesis was to understand the principles that dictate the design of efficient sensitizers. The efforts were focused on organic dyes combined with the newly developed high photo-voltage Cu(II/I) based electrolyte.