A recent patent by Pioneer suggests they can tweak the materials inside the individual colored phosphor subpixels to change the time delay for discharge. It sure sounded like they were addressing the color seperation problem but after reading the entire patent it seems more like they are adjusting the color reproduction (whiter whites.....)
"In addition, for the phosphor layer of the PDP according to the present invention, the red phosphor layer, the green phosphor layer and the blue phosphor layer respectively include different amounts of the secondary electron emission material determined in accordance with the electrification properties of the phosphor materials respectively used for forming the red, green and blue phosphor layers, such that the amounts of electrification of the red, green and blue phosphor layers are adjusted to be approximately equal to each other. Because of this adjustment, the discharge voltages in the red, green and blue unit light emission areas become approximately equal to each other so as to start the discharge approximately at the same time. In consequence, an increase in discharge voltage margin is achieved, thus achieving clearer white display.
Specifically, the discharge voltage required for initiating a discharge in the green discharge cell in which the green phosphor layer is formed is higher than those in the red discharge cell and the blue discharge cell. Accordingly, the discharge in the green discharge cell occurs slightly later than the discharge in the red and blue discharge cells. For this delay, even if the sustain discharge is initiated simultaneously in the red, green and blue discharge cells for a white display, the discharge intensity in the green discharge cell is reduced due to the time difference in discharge occurrence in the red, green and blue discharge cells, resulting in a magenta display instead of a white display."