Perovskites are a relatively recent addition to the world of solar panels but are responsible for increasing solar efficiency past the 19% efficiency barrier of the 1990s and early 2000s. However, as they heat up it has been shown that tunneling at the atomic scale results, lowering the peak efficiency. These researchers have shown that adding caffeine, of all things, to the mix increases the thermal stability of the layers and making them more efficient on top of it.
The superior crystallinity of the PVSK films containing caffeine boast reduced defect densities and better vertical charge transport, allowing for a champion PCE as high as 20.25% (compared to 17% for films without caffeine), he tells Physics World. The caffeine-containing devices are also thermally stable for over 1300 hours at 85°C (compared to just 150 hours for films without caffeine).