This thesis details the extension of time resolved x-ray absorption spectroscopy to the study of
organic photovoltaic (OPV) materials. These materials have attracted signi cant research interest due
to the potential to provide low cost, thin,
flexible solar cells which can be solution processed. Here,
we apply a tabletop, high harmonic generation based soft x-ray source to static and time resolved
x-ray absorption spectroscopy of poly(3-hexylthiophene) (P3HT), a widely studied material in OPV
research. The bandwidth of the attosecond HHG source and x-ray detection is sufficient to measure
the x-ray absorption spectrum at the sulfur L edge (165 - 230 eV) and carbon K edge (284 eV) simultaneously. This is combined with a 15 fs pump pulse at 2.25 eV to probe the dynamics after
photoexcitation of the pi - pi* transition relevant to solar energy conversion. Particular attention is
paid to characterising and minimising the effect of pump induced thermal heating and sample damage
which can obscure dynamical signals in these highly photosensitive thin film materials with low thermal
conductivity. To this end we characterise the temperature dependence of the x-ray absorption spectrum
of P3HT up to 225 C and propose and implement a methodology for minimising the effect of pump
induced heating on the experimental signal, without compromising the signal to noise ratio of the
measurement. At the sulfur L2,3 edge no photoinduced changes in the x-ray absorption spectrum are
observed within the experimental error, after accounting for thermal effects. At the carbon K edge,
transient differential absorption features are observed in the vicinity of the carbon 1s - pi* transition.
These are characterised over the first 100 fs following photoexcitation. Preliminary interpretation of
the signal is discussed.