I don't own a tritium sight equipped AR, but I used one in a class once. It had the rear planar sights as described by Mo_Zam_Beek, and worked just as he said except I didn't have much problem with the rear sights washing out the sight picture in total darkness. Maybe its the distance of the rear sight ring to where we each hold our eyes when sighting that different - don't know, but I could find a good sight picture in just about all situations and the rear sights appeared as blurred points to either side of my eye - not really even a part of the sight picture, more of just reference points so I knew to look between them when finding that black hole in the black rear sight ring in the dark...
Anyway, worked well for me and I've been wanting a set, or four, ever since. (I think I would be happy with just the front sight post too since I rarely have trouble even in the dark in finding the rear sight aperture - its that front sight that needs lighting up!)