Right now, silicon-based photovoltaics rule the production lines. That's good, in the sense that the silicon is cheap and abundant. But the form used in photovoltaic panels has to be exceptionally pure and processed heavily, which adds significantly to its cost. For that reason, research has continued into alternative materials for use in solar cells.
Based on the frequency that they appear in scientific journals, there's a class of substances that have materials scientists excited: perovskites. Originally named after a mineral, "perovskite" is now used to refer to any material that adopts the same crystalline structure as calcium titanium oxide.
Perovskites have some significant advantages, in that they can also be made from abundant and cheap elements, and many types of perovskite crystals will form spontaneously from a saturated solution. There are some downsides, however, as one of the best photovoltaic materials contains lead, which is toxic. Another problem is that one of the layers in perovskite cells tends to degrade rapidly in use. A just-published paper describes a new perovskite photovoltaic that, while still reliant on lead, gets rid of the problematic layer entirely.