Probing of carrier behavior in organic electroluminescent diode using electric field induced optical second-harmonic generation measurement

Abstract

By using the electric field induced optical second-harmonic generation (EFISHG) measurements, we probed the transient electric field in a double-layer indium zinc oxide (IZO)/N, N′-di-[(1-naphthyl)-N,N′-diphenyl]-(1,1′-biphenyl)-4, 4′-diamine(α-NPD)/tris(8-hydroxy-quinolinato)aluminum(III) (Alq3)/Al electroluminescent (EL) diode. Results evidently showed that EL was initiated by the injected hole transport across α-NPD layer, and holes accumulated at the α-NPD/Alq3 interface while EL was enhanced. Analysis based on the Maxwell–Wagner effect model well accounted for the hole accumulation. EFISHG measurement is useful as a tool for probing carrier behavior in organic EL devices.

Probing buried organic layers in organic light-emitting diodes under operation by electric-field-induced doubly resonant sum-frequency generation spectroscopy

“…This observation must be due to the doubleresonance effect, because the output SFG wavelength (in this work, x SFG ¼ x VIS þ x IR % 430 nm) is at the absorption edge of Alq 3 . When a static electric field E 0 is applied to the system, the SFG signal intensity (I SFG ) is given by [7][8][9][10][11][12][13][14][15][16] …”

Probing of Electric Field Distribution and Carrier Behavior in Double-Layer Organic Light-Emitting Diodes by a Novel Microscopic Electric-Field-Induced Optical Second-Harmonic Generation Measurement system

“…Noteworthy that the EFISHG measurement can selectively probe the static electric field formed in one of layers of double-layered devices by choosing an appropriate pulsed laser wavelength. In order to detect the electric field of the α-NPD layer, the wavelength of pulsed laser was set at 820 nm [10]. The electric field in the α-NPD layer of double-layer OLEDs illustrated in Fig.…”

“…Using this developed system, we have studied the electric field distributions in active layers in OFETs, OSCs, OLEDs, etc. [8][9][10][11][12]. However, to probe two-dimensional electric field distribution in devices, it is very useful to develop a system that allows electric field along the film-thickness direction to be directly probed.…”

Analysis of interface carrier accumulation and relaxation in pentacene/C60 double-layer organic solar cell by impedance spectroscopy and electric-field-induced optical second harmonic generation

“…Consequently, we are paying attention to electric-field-induced secondharmonic generation (EFISHG) measurement, which is available for directly probing the electric field distribution in organic devices in terms of carrier behaviors. 9,13,14 The EFISHG measurement coupled with IS measurement provides a clear understanding of interfacial phenomena related to the photovoltaic effect in OSCs.…”