The emission properties of liquid crystal (LC) electrochemiluminescent (ECL) cells were studied to realize various emission colors. The rubrene-doped cell showed markedly high luminance and current density, however, the properties cannot fully be explained by HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) levels of dyes. Next, the emission properties of LC-ECL cells doped with DPVBi- (4,4'-bis(2,2-diphenyl-ethen-1-yl)biphenyl) based fluorescent dyes substituted with methyl and butyl groups were investigated. The luminance was decreased by introducing those alkyl groups. It is considered that the disruption of the current balance of the radical cation and anion is caused by the electron-releasing alkyl groups.
