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

[17a-D102-1] Electron Spin Resonance (ESR) Direct Observation of Charge States in Light-Emitting Electrochemical Cells and Microscopic Elucidation of Device Operation Mechanism

〇Junya Katsumata¹, Fumiya Osawa¹, Go Sato¹, Kazumoto Miwa², Shimpei Ono², Kazuhiro Marumoto^1,3 (1.Univ. Tsukuba, 2.CRIEPI, 3.TREMS, Univ. Tsukub)

Keywords:light-emitting electrochemical cell, electron spin resonance, charge states

Light-emitting electrochemical cells (LECs) have recently attracted much attention because they have advantages such as high-efficient luminance and flexibility and they have simpler structures and lower driving voltages compared with organic light-emitting diodes (OLEDs). Although it has been known that they operate by the motion of electrolyte ions in light-emitting materials in LECs, the charge states and the operation mechanism of LECs have not yet been completely investigated from a microscopic viewpoint. In this study, we fabricated an LEC with a yellow light-emitting polymer material Super Yellow, and directly observed the charge states in the LECs during device operation using electron spin resonance (ESR) spectroscopy. As a result, we observed the increase in the ESR signal due to the bias-voltage application as well as the increases in the current density and the luminance. The analysis of the ESR signal directly indicates that the hole doping in Super Yellow takes place during device operation.