Solar cell principles, advances, new materials used in its production, applications and challenges

I want to do independent research about solar cells and to know more about the following goals :
1- principles of the solar cells ( how a solar cell works, different types, current materials, and technology being used for its production, etc )
2- what are the current applications of solar cells/what could be the future applications of solar cells and challenges
2- what are new advances in the production of solar cells ( new materials and technologies, benefits and challenges )