In electronics, doping silicon results in one of the most versatile functional materials ever employed. The pursuit of such functional materials in the optical domain is an area of great interest in the photonics community. I hope to convince you that whatever route photonics takes, a class of materials known as phase change materials, will play a key role in its commercialization. These materials can be addressed electrically, and whilst this can be used to control optical signals on photonic circuits this can also be used to create displays and smart windows. In this talk, I hope to give an overview of these applications of these materials with a view towards their near-term applications in displays, and their longer-term potential in integrated photonic memories to photonic machine-learning hardware components, with a few of our recent results in this area.