There are other technologies. Nuclear isomers for example have a lot of potential, but the fossil fuel hegemony really keeps alternatives from flourishing. We can be very thankful that photovoltaics was invented pre-WII, otherwise I doubt we'd be seeing it today either.
That's not really how it works. Technologies are either commercially viable or they are not. The thing that enabled windpower and solar power to take off is economic parity with other means of generating power. Photovoltaics and windpower being 'invented' (as if it isn't blatantly obvious that there is energy in wind and solar and that this energy can be captured in a myriad of ways) before a certain date has nothing to do with whether or not we see them today.
Tons of money and effort has been sunk in attempts to create more sources for energy and some of those have paid off and others are still under review. The 'fossil fuel hegemony' is actually quite a large investor in more than a few projects, their product is energy, not a particular kind of energy.
Who on earth told you that? Hafnium doesn't work - DOE and DOD moved mountains in the nineties trying to get it to work and a number of people lost their careers and sanity in the process. But you go ahead and tell yourself that it's the "fossil-fuel hegemony"
The first practical high efficiency (6%) cell was made in Bell Laboratories in 1954. It was the first PN junction silicon solar cell, the technology that still powers 90% of solar cell modules on the market.
