Engineers at the University of New South Wales in Sydney have claimed a new efficiency record for perovskite solar cells.
The team, led by Anita Ho-Baillie, Senior Research Fellow at the Australian Centre for Advanced Photovoltaics (ACAP) demonstrated an efficiency rating of 12.1 per cent on a 16cm² perovskite solar cell. The results, verified by international testing centre Newport Corp, represent the highest efficiency rating with the largest perovskite solar cells to date.
Perovskite is a structured compound, where a hybrid organic-inorganic lead or tin halide-based material acts as the light-harvesting active layer. They are the fastest-advancing solar technology to date, and are attractive because the compound is cheap to produce and simple to manufacture, and can even be sprayed onto surfaces.
To make perovskite solar cells, engineers grow crystals into a structure known as ‘perovskite’, named after Lev Perovski, the Russian mineralogist who discovered it. They first dissolve a selection of compounds in a liquid to make the ‘ink’, and then deposit this on a specialised glass that can conduct electricity. When the ink dries, it leaves behind a thin film that crystallises on top of the glass when mild heat is applied, resulting in a thin layer of perovskite crystals.
Most of the world’s commercial solar cells are made from a refined, highly purified silicon crystal and, like the most efficient commercial silicon cells need to be baked above 800˚C in multiple high temperature steps. Perovskites, on the other hand, are made at low temperatures and 200 times thinner than silicon cells.
“This is a very hot area of research, with many teams competing to advance photovoltaic design,” said Ho-Baillie. “Perovskites came out of nowhere in 2009, with an efficiency rating of 3.8 per cent, and have since grown in leaps and bounds. These results place UNSW amongst the best groups in the world producing state-of-the-art high performance perovskite solar cells. And I think we can get to 24 per cent within a year or so.”
Her team has also achieved an 18 per cent efficiency rating on a 1.2 cm² single perovskite cell, and an 11.5 per cent for a 16cm² four-cell perovskite mini-module, both independently certified by Newport.