According to a report from The Telegraph (paywall), it seems that Apple was rumored to be in talks with a British company by the name of Nanoco who specialized in quantum dot technology. This technology would allow camera sensors to gather more light more efficiently compared to more traditional silicon designs. The deal with Nanoco was reported to be worth tens of millions, but apparently Apple had decided to back out of it after finding out how expensive these sensors would cost to produce.
There is no way to know if Apple was ever in talks with the company in the first place, but that seems to be what some had believed to be. This deal, if successful, would have potentially allowed future iPhone cameras to take better photos in low-light and could also help with augmented reality. It is now reported that Apple has since decided to go with an alternative tech in the form of laser-powered 3D scanning that will make its debut in the 2020 iPhone.