I know you can freeze them, but then you can only use them to cook with. I want to keep them fresh as long as possible.
How to Preserve Red Bell Peppers
I've been able to keep uncut green peppers for about two weeks - keep them in the fridge, unwashed, in the crisper part of your fridge. Sometimes sealing them in ziplock type freezer bags (not the lite-weight sandwich types) from which you have expelled all the air before sealing will help them to keep longer.Keep freshly harvested vegetables/fruit separate from the ones that have been cut. Reds probably won't keep as long as they are actually a more mature fruit to begin with.