Fluorescence from copper phthalocyanine thin films was first observed using tunneling electrons from a scanning tunneling microscope on the Au substrate. The plasmon enhancement effect enables the detection of the fluorescence emission even though the intrinsic fluorescence from a copper phthalocyanine molecule is extremely weak. Moreover, this emission appeared under an energy-forbidden condition, where the fluorescence at the energy of similar to 1.7 eV could be observed with bias voltages lower than 1.7 V. As the threshold bias voltage of this emission is similar to 1.1 eV, this emission can be explained by the up-conversion transfer resulting from the plasmon-enhanced triplet-triplet annihilation of molecules. (C) 2007 Elsevier B.V. All rights reserved.