Revealing nanoscale phase separation in small-molecule photovoltaic blends by plasmonic contrast in the TEM

► Energy filtered TEM for imaging phthalocyanine:C60 blends by spectroscopic contrast. ► Plasmon energy shifts according to composition but different for blends and bilayers. ► Temperature induced phase separation is visualized with sub-10 nm resolution. ► Plasmon map discloses complete lateral distribution independent of crystallinity.