The application of Cu(I) phenanthroline dyes in DSCs with optimized I⁻/I₃⁻ and Co(II/III) electrolytes

Abstract

The world faces an energy and climate crisis. After an unprecedented worldwide increase in energy consumption, which has largely been based on the use of fossil fuels, mankind is challenged by global warming and its consequences. The demand for renewable energy has focused our attention on capturing the inexhaustible solar energy. Photovoltaic (PV) devices based on silicon have been and remain the most popular choice. However, the high purity demands of this technique are a drawback for cheap energy production from solar power. Dye sensitized solar cells (DSCs) are a valuable alternative for low-cost PVs since the separation of light-harvesting and charge transport implicates less stringent purity demands of the built-in compositions. Replacing rare ruthenium used in Gratzel-type n-type DSCs by more Earthabundant and sustainable metals is a goal of our research group. This thesis describes the use of heteroleptic Cu(I) dyes using phenanthroline ancillary ligands to harvest light. Chapter 1 gives a short overview of the current energy problems and outlines the current status of the literature relevant to this thesis. Chapter 2 describes the methods for the characterization of the investigated dyes and their application in dye sensitized solar cells (DSCs). Chapter 3 shows the synthesis and characterization of ligands and of copper(I) complexes designed for application in DSCs. Chapter 4 compares the performances of DSCs containing heteroleptic Cu(I) complexes made from [Cu(13)2][PF6] (ligand 13 contains a peripheral hole-transporting NPh2 group) and four different anchoring ligands with carboxylic acid (ALC1) or phosphonic acid (ALP, ALP1 and ALP1 TBA) anchors. Chapter 5 investigates the differences between heteroleptic Cu(I) dyes from several phenanthroline based ancillary ligands in combination with anchoring ligand ALP1. Chapter 6 deals with the optimization of I−/I3− electrolytes for [Cu(15)(ALP1)]+ sensitized solar cells (ligand 15 contains a peripheral hole-transporting domain related to that in ligand 13). Chapter 7 shows the incorporation of [Co(bpy)3][PF6]2/3 electrolyte in DSCs using [Cu(13)(ALP1)]+ and [Cu(15)(ALP1)]+ sensitizers. Chapter 8 lists the experimental details. Chapter 9 concludes the work and gives an outlook for future work.