What is Perovskite?

To clarify, the perovskite structures that prove so much potential in solar power research are various materials comprising different permutations of atoms. These are all based on the structure of perovskite; specifically calcium titanate, which Gustav Rose discovered in the Ural mountains and named to celebrate fellow mineralogist Lev Perovski.

The word ‘perovskite’ can now refer to a substance where the elements in CaTiO₃ are replaced, to improve the efficiency and flexibility of solar panels, and even suit certain light wavelengths.

Calcium 2+
Titanium 4+
Oxygen 2-

These ions can be substituted, but this needn’t be with single atoms; the most common form of perovskite, developed in 2015, is methylammonium lead halide (MAPbI₃):

A methylammonium cation (CH₃NH₃⁺) at the centre of MAPbI₃ (Christopher Eames et al.)

In solar cells, perovskite’s structure makes it exceptionally good at capturing sunlight and converting it into electricity.

Wide Bandgap Perovskites

The “bandgap” refers to the slice of the solar spectrum a material can absorb. A wide bandgap perovskite is tuned to harvest the higher-energy, blue part of sunlight. This makes it ideal for use in tandem solar cells, where a perovskite layer sits on top of a traditional silicon cell. The perovskite absorbs the blue light, while silicon collects the red. Together, they make far better use of the sun’s full spectrum.

In principle, this pairing can push solar efficiency well beyond today’s silicon limits. In practice, as the new study shows, the challenge is ensuring these fragile wide bandgap perovskites last long enough to power the real world.