While I can't speak to the specific interest of solar cells, Perovskite is the primary ore source for Titanium. Owing to the fact that alloys of Titanium played a critical role in modernization of weapons technologies that occurred during the cold war period, there was a LOT of research money into titanium projects during the 1970s to early 1990s. For instance, the hull of the SR-71 blackbird is a special titanium alloy that allows it to fly at MACH 3 and at >100,000 ft (also while its top secret there's some evidence that radar deflecting paints have titanium in them). As such, defense money in the US and former CCCP was pouring into anything even remotely titanium related (analogous to Machine Learning stuff today). I'd imagine once people found out that perovskite was actually decent for the solar cell stuff that created a reinforcing effect, where grant writers and readers both bought into giving money to this subset of solar cell research, as it was established science.
TL;DR: If I was a solar cell research a couple decades ago, I'd write a perovskite related grant to get a lot of money, and everything snowballed from that.