What's the principle behind SSL ?

One question that often pop's up in the context of Solid state lighting is what the fuss is all about. What it's all about is a fundamental technology change in generating light. While gas discharge tubes were a good innovation (incandescents are typically heating coils, nothing novel except it happened 100 years back). The material properties of different semi-conducting materials and their respective dopants are used to generate light via electro-phoresence. this is the direct conversion of electricity into EMR in the visible range. That is the magic..