Crystallisation behaviour of PCDTBT in thin films

Chapter 1 introduces the reasons behind this study, the importance and applications of PCDTBT in organic electronic devices, thus the importance of understanding how confinement in thin films influences the crystallisation of this polymer which will have an impact on the electronic properties of the material. Chapter 2 describes the analytical techniques used (ellipsometry, atomic force microscopy and grazing incidence X-ray scattering) and their importance for this study. In chapter 3 is reported the thermal protocol that allowed the understanding of the crystallisation of PCDTBT; ellipsometry, GIWAXS and AFM results are reported in order to understand the importance of the protocol and also aid the comprehension of the rest of the thesis. Chapter 4 describes how different annealing temperatures influence the crystallisation kinetics and the amount of crystallinity in a sample. Chapter 5 looks in detail at a phenomenon occurring in the film that was quite unpredicted: the ellipsometry data are used to follow the change of the thickness of the film under the thermal treatment explained in chapter 3; an initial shrinking at the ellipsometry shows the crystallisation phenomenon, but what is causing a second expansion which is following the crystallisation. In chapter 6 is finally reported the influence of the film thickness on the crystallisation properties of the material; the influence of the two interfaces on its ordering is key in understanding how to improve the efficiency of organic electronic devices.