(a-b) The brightness of HELIOS 70EL increases with the increase in thickness in the dielectric-EL (t = 100 µm vs t = 1500 µm) when comparing with the same E and frequencies applied. The measurements were repeated on three samples and the error bars represent the standard deviation. The luminance and the operated fields on the HELIOS devices are expressed using the equation of L = Lo exp(−b/E0.5). Insets show the photographs of the oblique view of the HELIOS device. (c-d) Photographs showing that the HELIOS-thick 70EL device is significantly brighter than the HELIOS-thin 70EL device.