I spent most of my PhD working on conducting plastics for making solar cells. The idea behind the plastics (or more specifically, conjugated polymers) is that they would be cheaper to make than silicon. They’re not very efficient, but they only have to be efficient enough to outweigh the cost of the substrate that they’re printed on. Conducting plastics can be ink-jet or screen printed, just like making a t-shirt. They’re still a ways out from commercial production though (5-10 years) because of their low efficiency (though this is improving), and also because they don’t last very long. Silicon’s a workhorse that way, it keeps making electricity for at least 25 years. The polymers only last about a year or so… they degrade when exposed to air or sunlight. What a drag. So, they may be a niche application (think temporary installations like billboards) unless that problem is solved.
I’ve written quite a bit about solar energy and its cost effectiveness, and also have a few activities you can use in your classroom on solar energy. You can check out my solar energy writing and activities. If you have any questions on this stuff, post it here — I answer my comments!