[19a-C212-1~10] 12.4 Organic light-emitting devices and organic transistors

△ [19a-C212-10] Investigation of selective triplet exciton formation in a single molecule by luminescence measurements using an STM

〇(DC)Kensuke Kimura^1,2, Kuniyuki Miwa^1,3, Hiroshi Imada¹, Miyabi Imai-Imada^1,2, Shota Kawahara^1,2, Jun Takeya², Maki Kawai^2,4, Michael Galperin³, Yousoo Kim¹ (1.RIKEN SISL, 2.Univ. Tokyo, 3.UCSD, 4.IMS)

Keywords:Scanning Tunneling Luminescence, Triplet exciton, Single molecule electroluminescence

We conducted single-molecule investigations of electroluminescence using a scanning tunneling microscope (STM) to a PTCDA molecule on NaCl film grown on Ag(111) substrate. PTCDA shows both phosphorescence and fluorescence at high applied voltage. In contrast, only phosphorescence occurs at low applied voltage, clearly indicating the selective formation of triplet exciton without singlet exciton. The combination of luminescence and differential conductance measurements reveals that spin-selective electron removal occurs from a PTCDA molecule. Our findings clearly show that the electron transport and the exciton formation mechanism can be controlled by manipulating a spin inside a molecule.