Domain composition and interfacial structure are critical factors in organic photovoltaic performance. Here, we report neutron reflectivity, grazing-incidence X-ray diffraction and atomic force microscopy measurements of polymer/fullerene thin-films to test a hypothesis that these partially miscible blends rapidly develop composition profiles consisting of coexisting phases in liquid-liquid equilibrium. We study a range of polymer molecular weights between 2 and 300 kg mol −1 , annealing temperatures between 120 and 170 o C, and timescales up to 10 min, yielding over 50 distinct measurement conditions. Model bilayers of fullerene-derivatives and polystyrene enable a rigorous examination of theoretical predictions of the effect of polymer mass and interaction parameter on the compositions, ϕ, and interfacial width, w, of the coexistent phases. We independently measure ϕ and w and find that both Flory-Huggins mean-field-theory and key aspects of self-consistent-field-theory are remarkably consistent with experiment. Our findings pave the way for predictive composition and interface design in organic photovoltaics based on simple experimental measurements and equilibrium thermodynamic theory.

The thermal behaviour of small-molecule/polymer mixtures is of crucial significance in relation to the operational stability of organic photovoltaics, and the equilibration (or otherwise) of domain compositions and interfaces is...

The fullerene diffusion and interfacial broadening onset in bilayers is strongly correlated with the Mw-dependent molecular mobility of the polymer.

Organic photovoltaic (OPV) devices use polymers and small-molecules, such as fullerenes, and offer an alternative to conventional inorganic devices. To achieve commercial success OPV devices require well-controlled morphologies and increased device lifetimes. The film morphology of these devices is complex: both mixing and crystallisation can occur. In this thesis, the fundamental behaviour of two model polymer/fullerene systems is investigated. The impact of parameters such as film thickness, molecular weight (MW) of the polymer and annealing temperature, on crystallisation and mixing are examined.

This paper examines beach plastics in a pie chart by proportionality using previous studies that developed characterisation techniques. These techniques include inferring industrial sources of plastic pollution. This paper combines these methods with a comparison of industry patent statistical proportion for geographical origin inference.

This paper analyses crystal properties of PCBM when annealed in a bilayer with PS on the top. There are intriguing formations and definite thresholds to the varying reproducible morphologies found. This paper suggests that the PS layer greatly influences PCBM crystal nucleation rate and final morphology.

This paper outlines experimental results on a model system of PCBM and PS for control parameter exploration of PCBM crystallisation. PS layer attributes, and annealing temperature amongst others are the variables explored.