[17a-D102-1~10] 12.4 Organic light-emitting devices and organic transistors

[17a-D102-5] Real-time Probing of Carrier behavior in OLEDs by time-resolved Electric-field induced Sum Frequency Generation Spectroscopy

〇Takayuki Miyamae¹, Noriyuki Takada¹, Hiroshi Ohata², Tetsuo Tsutsui² (1.AIST, 2.CEREBA)

Keywords:sum-frequency generation, charge carrier

Time-resolved electric-field-induced sum-frequency generation (EFI-SFG) spectroscopy was employed to study the charge behavior of multilayer organic light-emitting diodes (OLEDs). Through application of the square wave pulse bias to the OLEDs, compensation for the polarization charges in the electron transport layer and the generation of 4,4'-bis[N-(1-naphthyl-N-phenylamino)-biphenyl] (α-NPD) cations were observed. When the pulse voltage was turned off, the α-NPD cations immediately disappeared, confirming that charge recombination occurs at the interfaces. We therefore concluded that time-resolved EFI-SFG is useful for directly probing the carrier behavior in OLEDs in addition to identifying the origin of the charge carriers present in OLEDs.