Fig. 1
From: Interfacial width and phase equilibrium in polymer-fullerene thin-films
A summary of the behaviour of PS/PCBM bilayers as a function of PS Mw, annealing time and annealing temperature. a A schematic diagram of the rapid diffusion of PCBM into the top (PS) layer. b The scattering length density (SLD) profiles from a 5k-PS/PCBM sample before and after annealing (in-situ). c–d A selection of neutron reflectivity curves and fits (bilayer fits with Gaussian roughness39,50 at all interfaces) for a range of different Mw samples annealed for various times at a range of temperatures. Curves are offset vertically for clarity. e SLD profiles at the buried PCBM/PS-rich interface, corresponding to fits from a selection of the 2k-PS, 20k-PS and 300k-PS samples. The full SLD profiles, showing the SLDs from the substrate out to the sample surface, along with the corresponding reflectivity data and fits for a further selection of samples are shown in Supplementary Fig. 2. f A Grazing-incidence X-ray diffraction GIXD detector map from a typical annealed bilayer (5k-PS/PCBM annealed at 145 oC for 5 min), with the in-plane and out-of-plane components of the momentum transfer represented as Qx and Qz, respectively (see Môn et al.43). g A GIXD detector map from a crystallised PCBM single layer annealed at higher temperatures and for longer times than used in the present bilayer study (170 oC for 2 h). h A transmission electron microscopy image of a PCBM crystal in an annealed 300k PS/PCBM bilayer (scale bar = 3 μm). Apart from the SLD profiles shown in b, all data in this figure is from ex-situ annealed samples. The error bars in c and d are standard deviations, calculated from the neutron count data (error bars that are not visible are smaller than the data symbols)
