Here's their Wikipedia page
with a basic outline and there's also some good info on the Ubique
There is a book, The History of the Sikh Pioneers
by MacMunn (1936).
More detail on their Afghan service in particular is given in Shadbolt (1882, reprinted 1974 and 2001) and they of course come up several times in some of the better histories (Official Account
(1908) and Robson (1986, reprinted 2003)).Osprey
have a couple of books on Indian regiments in general which contain a little info and there are other good general Indian army books - eg. The Indian Army of the Empress
(Harfield 1990), though that is ordered by campaign, so you might have to hunt out any minor mentions; but it's an excellent overview.
Best - Garen