Well the point of lighting a room is that you want the room `light` and making walls that absorb light makes them not reflect light and then your room is dark a

Well the point of lighting a room is that you want the room `light` and making walls that absorb light makes them not reflect light and then your room is dark again. So even if this was possible (which it is not), the idea would still be rather useless (until you managed to achieve efficiency over 100 % ;) ).