Being an Engineer, I must say (that) the topic itself is quite broad in nature.

If you want to have complete "information" about LED, you first need to understand the semi-conductors, doping, sort of depletion region etc.

Underlying gist is that, which I assume and firmly believe, this topic must be touched from the surface. What I really mean to say is that you need to be aware of its basic functionality - which is hardly going to be asked, its significance - which is incredibly important and vital, and how it can make a prominent, economical difference by preferring LED lighting to incandescent bulbs and compact fluorescent lamps. Some facts - real and authentic - related to LED lighting must be gathered from internet. Take the countries like US, UK etc. and take their figures for comparison, or maybe for devising the plan for the betterment of Pakistan's economy by comparing it "with" their plan of LED lighting.

I do not have my notes with me right now, but I do remember the link, which is energy.gov. Go there and explore a bit about LED lighting(for practical usage). Other than that, the basic functionality you can get about it from the wikipedia page, or you may explore YouTube and type in the search "Light emitting diode".

Regards.