[19p-G202-1~12] 12.2 Characterization and Materials Physics

△ [19p-G202-7] Effect of Elemental Substitution on Field Modulation Spectrum in Proton-transfer-type Organic Ferroelectrics

〇(M2)Yohei Uemura¹, Shunto Arai¹, Junya Tsutsumi², Satoshi Matsuoka², Sachio Horiuchi², Tatsuo Hasegawa^1,2 (1.U. Tokyo, 2.AIST)

Keywords:organic ferroelectrics, electric field modulation spectrum, domain observation technique of ferroelectrics

Proton-transfer-type organic ferroelectrics are a novel class of ferroelectrics composed of small molecules linked by hydrogen bonds, whose spontaneous polarizations are reversed through the cooperative transfer of protons exhibiting small coercive field (3 – 20 kV/cm). Since these materials are soluble in many types of solvent, they are expected to be applicable to the printed electronics devices operating at low voltages. We have been studying the ferroelectric properties of these materials in thin films toward the device application. Especially, we have focused on the large visible light absorption of π-conjugated molecules, and have reported that the ferroelectric domains could be visualized by using the change of absorbance induced by external electric field. This time, we focused on that the difference of halogen atoms of substituent leads to the difference of ferroelectric properties (such as transition temperature or coercive electric field) even though those materials have same crystal structures and same molecular structure. We investigated the effect of the elemental substitution on the ferroelectric properties based on the field modulation spectrum; difference of absorbance between under forward and reverse bias applications. As a result, it was observed that the difference of the substituent causes the different response of optical spectrum for external electric field. From this result, it was indicated that the protons in hydrogen bonds exhibit different behavior under electric field depending on substituent.