Mutual enhancement between plasmon and molecular fluorescence of conjugated polymer on metal substrates induced by STM

The STM-induced luminescence of a conjugated polymer poly[2-methoxy-5-(2′-ethyl-hexyloxy)-p-phenylene vinylene] (MEHPPV) on metallic substrates of Ag(1 1 1), Ag, Au and Cu and ITO have been investigated in air at room temperature by using Ag or Pt–Ir tip. Molecular fluorescence of MEHPPV was observed from the polymer film on Ag(1 1 1), Ag and Au substrates, and all of them show an intensity enhancement compared to the pure substrates. A mutual enhancement between surface plasmon and molecular fluorescence is suggested for the STM-induced luminescence of MEHPPV on these substrates.