I study Materials Engineering and we do a lot on solar cells and other forms of energy generation (fuel cells/nuclear/etc).
It isn't a mature technology, and from what I've seen most work and innovation is done at universities rather than in industry (I know in the US it is heavily subsidised so is growing, but I think an american could talk more intelligently about that). Solar was the first thing BP cut when it was trying to recoup its losses from that oil slick, which suggests its research was more of a PR exercise than a viable business model.
Australia has a lot of research and give pretty generous stipends for PhD students there:
http://www.australiansolarinstitute.com.au/ - offers AU$40,000 per year (which is really good)
http://www.pv.unsw.edu.au/ - UNSW is a pretty good uni for a PhD, and has a dept dedicated
In the UK, any decent Materials department will have a group looking a photovoltaics. Look at Birmingham, Manchester, Oxford, Sheffield, Sheffield Hallam, Cambridge, Liverpool and Imperial. I know a guy doing an EngD at UCL looking at organic PV cells as well.