Since Iphone 6, all Iphone models have had a protruding camera on the back. It's because the camera module itself can not be thinner without tumbling on the image quality, but in the future it may not be needed anymore.
Apple has purchased Invisage Technologies, a company that develops a revolutionary new technology for image sensors. The technique is called Quantum film and covers a silicon circuit with a special light-sensitive surface layer consisting of quantum points.
Basically, it is the same technology as quantum dot tv, but here it is used to interpret the incoming light instead of displaying a picture on a screen.
Quantum movie pixels can capture more photons, store more electrons and reproduce colors better, write Invisage about their technique.