Influence of hole injection layer and work function of cathode on the performance of light-emitting liquid crystal cells with fluorescent dye-doped nematic liquid crystal

Abstract

We investigated the properties of rubrene-doped nematic-liquid-crystal cells to help determine the appropriate structure and material of electrodes for inducing light emission. In particular, we addressed the influence of the insertion of a hole injection layer (HIL) and the work function of the cathode on device performance. As a result, the employment of a HIL and a lower-work-function material was revealed to be effective in obtaining higher luminance and external quantum efficiency. We concluded that this improvement is caused by the facilitated carrier injection on the HIL and cathode surface, as is true for common organic light-emitting diodes.

Bright Yellow Electrogenerated Chemiluminescence Cell Using a Rubrene Solution Doped with an Emitting Assist Dopant

“…7 Improving methods for the ECL performance of the rubrene-based cells have been investigated by many researchers. [8][9][10][11][12][13] In 2001, Nishimura et al demonstrated a bright yellow emission of rubrene with a maximum luminance (L max ) of 183 cd m ¹2 at a direct current (DC) voltage of 8 V. 12 In their study, the ECL solution was prepared by dissolving rubrene with 1,2-diphenoxyethane (DPE) as an ion conductive assist dopant in a mixed solvent of acetonitrile (ACN) and 1,2dichlorobenzene (1,2-DCB). In 2021, Kim et al evaluated the ECL performance of rubrene dissolved in a tetrahydrofuran (THF) solvent under an alternating current (AC) voltage, and an L max of over 30 cd m ¹2 was observed at a frequency of 60 Hz.…”