1:15 PM - 1:45 PM
[15p-1G-1] [Molecular Electronics and Bioelectronics Award Speech] Analysis of carrier dynamics as dielectric polarization phenomena in organic films: EFI-SHG and MDC
Keywords:Electric field induced Optical Second Harmonic Generation,Maxwell Displacement Current,Organic Electronics
Probing and modeling of carrier motions in materials as well as in electronic devices is a fundamental research subject in science and electronics. According to the Maxwell electromagnetic field theory, carriers are a source of electric field. Therefore, by probing dielectric polarization caused by the electric field arising from moving carriers and dipoles, we can find a way to visualize the carrier motions in materials and in devices. The techniques used here are an electrical Maxwell-displacement current (MDC) measurement and a novel optical method based on electric field induced optical second harmonic generation (EFISHG) measurement. The MDC measurement probes changes of induced charge on electrodes, while the EFISHG probes nonlinear polarization induced in organic active layers due to coupling of electron clouds of molecules and electro-magnetic waves of incident laser beam in the presence of DC field caused from electrons and holes. In this presentation, the concept for probing electron and hole transport in solids by using the EFISHG is discussed, then I visualize carrier transit in organic devices, i.e., organic field effect transistors, organic light emitting diodes, organic solar cells, and others. I also discuss the concept of the detection of rotational dipolar motions in monolayers by means of the MDC measurement, which is capable of probing the dielectric spontaneous polarization formed by dipoles in organic monolayers. Finally I conclude that ideas and experiments on EFISHG and MDC lead to a novel way for analyzing dynamical motions of electrons, holes, and dipoles in solids, thus these are available in studies of fundamentals and applications in electronics.