Soft materials employing organic molecules are among the front-running candidates for next-generation solar cells. They offer lightweight, flexible characteristics which are cheap to produce and implement, making them more promising than commercially available inorganic photovoltaics. Furthermore, the possibility to tune the molecular structure of organic components presents an infinite pool of opportunity in the endeavour to enhance photovoltaic performance. This thesis evaluates a collection of soft materials from various perspectives that are currently at the forefront of photovoltaic research. The investigations described herein aim to elucidate the mechanisms contributing to photovoltaic performance by application of time-resolved
spectroscopic tools.
Chapter 3 examines the effects of chemical structure modification on small molecule components for organic photovoltaic devices. Two studies are presented, both of which describe a regioisomeric modification on a molecular structure that is incorporated into a photovoltaic blend. In both cases, transient absorption spectroscopy reveals stark contrasts in the materials’ exciton and charge dynamics which strongly influence their propensity for photovoltaic charge generation. The discussion highlights the dramatic consequences of minor structural differences in organic photovoltaic components, which emphasises the immense potential for their development.
Chapter 4 considers the operational stability of photovoltaic devices comprising soft materials,
which is a major hurdle currently hindering their industrialisation. Two studies are presented, in
which charge dynamics unravelled by transient absorption spectroscopy are used to rationalise
the studied materials’ lifetimes under operational conditions.
Chapter 5 explores the natural biological apparatus for photovoltaic light-harvesting by examining photosynthetic microorganisms. A range of electrochemical and time-resolved spectroscopic methods are employed in order to investigate photoinduced processes in cyanobacteria in biophotovoltaic devices as well as in vivo.
Overall, the research demonstrated in this thesis establishes fundamental findings for advancing
soft photovoltaic materials. The insights regarding photophysical processes and optoelectronic properties of the studied systems highlight crucial lessons for material optimisation which could aid in their development, contributing to the goal of commercialisation.