French site Lesnumeriques posted an article on Samsung's KN55S9C curved OLED TV, in which they include a macro-photo showing the TV's sub pixels up close:
As you can see, the blue subpixels are bigger than the red and green ones (about twice as large). This was designed this way because the blue OLED has the lowest lifetime - if it is bigger then you can lower the brightness and so conserve lifetime. We've seen many OLED displays with differently-sized subpixels - including PenTile ones and the rather unique display used in the Note 2.
It seems that each subpixel is made from two actual diodes (look closely for example on the bright red subpixels inside the green frame above). In addition, the light seems to be scattered to the sides of those diodes (and so you'll see dimmer light to the sides of the actual sub pixels).
LG is using a different architecture for their OLED TVs. The so-called WRGB structure uses four white sub pixels (made from yellow and blue emitters) with color filters on top: white (unfiltered), red, green and blue. As you can see from the photo above, the white sub pixel is actually larger than the colored ones. The white sub pixel is added to increase brightness and efficiency.