The plasmon feature in an electron energy loss spectrum provides unique insight into poly(3-hexylthiophene) (P3HT)-phenyl-C61-butyric acid methyl ester (PCBM) solar cells. Analysis of the intensity, shape, and energy of the plasmon reveals information about the type of phase, distribution of P3HT semi-crystalline fibres, and PCBM packing density at high spatial resolution. Plasmon-loss imaging has also revealed nano-scale residual solvent pockets with preferentially dissolved PCBM. A robust tomography method for reconstructing the 3D morphology of the bulk heterojunction thin-film via plasmon-loss images is also presented. The analysis techniques can be used to investigate morphology evolution during thin-film processing and its effect on device performance.

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