Have you considered finding some heavy duty wall anchors. Depending on how heavy the material is, this may be able to hold the weight. I would consult someone at the hardware store first.
Painting the wall a brighter color would be a great way to brighten it up. If adding a larger window isn't in your budget, consider adding some soft lights around the room. If you use soft lamps with bulbs that aren't too intense, you can possibly re-create to feel of natural light.