A Novel Microscope for Visualizing Electric Fields in Organic Thin Film Devices Using Electric-Field-Induced Second-Harmonic Generation

Abstract

We have developed a novel microscope for visualizing electric fields in organic thin film devices on the basis of electric-field-induced second-harmonic generation (EFISHG) measurement. By using a radial polarized laser beam as a probing light, we showed that the electric field formed in metal–C60–metal diodes in the film-thickness direction is visualized. The developed microscope has a potentiality in directly visualizing carrier motion in thin-film devices such as organic solar cells.

A Novel Microscopic Analyzing System for Characterizing Organic Light‐Emitting Diodes Using EFISHG and LBIC Measurements

“…In addition, aiming at a more detailed exploration of real-space carrier behaviors inside MIM devices, we developed a microscopic EFISHG system using radially polarized pulsed laser as a modification of conventional EFISHG measurement [13]. Besides, using this method, we reported on relationships between electric field distribution, interfacial charge distribution, and EL intensity in fullerene single-layer devices and double-layer OLEDs [13,14]. Besides, using this method, we reported on relationships between electric field distribution, interfacial charge distribution, and EL intensity in fullerene single-layer devices and double-layer OLEDs [13,14].…”

“…Thus, we analyzed internal electric fields and carrier behaviors in OLEDs, OSCs, organic transistors, and other devices by means of electric-field-induced optical secondharmonic generation (EFISHG) measurement method that is focused on induced polarization phenomena due to electric field formed in organic materials [7,8,[11][12][13][14]. For example, we measured electric field strength in organic layers along light-emitting surface and electric charge accumulated at organic/organic interface of double-layer OLED, and demonstrated existence of two light emission modes that bring about interfacial charge accumulation in case of ac-driven OLED [8].…”

“…We also showed possibility of visualizing charge migration inside organic transistor channels [11], and explained how electric charges expand in organic film [12]. In addition, aiming at a more detailed exploration of real-space carrier behaviors inside MIM devices, we developed a microscopic EFISHG system using radially polarized pulsed laser as a modification of conventional EFISHG measurement [13]. This system makes possible direct measurement of electric field strength in the thickness direction of organic films in MIM devices such as OLEDs and OSCs; local in-plane electric field distributions and interfacial charge distributions can be evaluated by sweeping a laser beam across the surface.…”

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

“…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.…”

“…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. Therefore we have been developing a novel microscopic EFISHG measurement system equipped with an apparatus that can incident a radially polarized pulsed laser beam in the direction along the film-thickness direction [12].…”