Perovskites are synthetic compounds that – in some ways – are a better alternative to the silicon semiconductors currently utilized in solar cells. And while there are still some hurdles to be crossed, a new application process could soon help them enter widespread use.
Among the advantages of perovskites is the fact that they absorb light and convert it to energy more efficiently than silicon.
Additionally, solar cells made with them would likely be cheaper to manufacture. This is because while silicon semiconducting material has to be produced at very high temperatures and then cut into wafers, liquid perovskite can simply be sprayed onto glass and allowed to dry.
Perovskite solar cells would be particularly effective if different types of perovskites – each one optimized for a different quality – could be added in successive layers. Unfortunately, though, freshly-sprayed layers of liquid perovskites tend to dissolve the dried layers to which they're applied.
In order to get around this problem, scientists at Thailand's Mahidol University developed a process known as sequential spray deposition. This involves converting a liquid into very fine droplets before applying it to a surface.
After some tweaking of various parameters – which included raising the application temperature to around 100 ºC (212 ºF) – the researchers were successfully able to apply a highly stable type of perovskite to a dried layer of another type that had better electrical qualities. The resulting solar cell not only exhibited two clearly-defined layers, but it also combined stability with good electrical performance.
"Our work demonstrates a process to deposit perovskite layer by layer with controllable thicknesses and rates of deposition for each layer," says the lead scientist, Dr. Pongsakorn Kanjanaboos. "This new method enables stacked designs for solar cells with better performance and stability."
The research is described in a paper that was recently published in the journal Optical Materials Express.
Source: The Optical Society