Engineers from the University of NSW have boosted their perovskite solar cells to a record 12.1% efficiency, with promises of even higher efficiencies.
Perovskite is a structured compound, where a hybrid organic-inorganic lead or tin halide-based material acts as the light-harvesting active layer.
Perovskite solar cells are of interest to researchers because they are flexible, cheap to produce, and simple to make -- they can even be sprayed onto surfaces.
A solution deposition of perovskite is so versatile that it can also be printed or painted on solar cells. The chemical compositions allow the cells to be transparent, or made of different colours. With perovskite solar technologies, it may be possible to cover every surface of buildings, devices and cars with solar cells.
This is in contrast with the current dominant form of solar cells, which are made from a refined, highly purified silicon crystal, needing to be baked above 800˚C in multi high-temperature nature steps. Perovskites, on the other hand, are made at low temperatures and 200 times thinner than silicon cells.
Despite their promise of more versatile and cost-effective solar electricity generation, perovskites still face many issues, including their vulnerability against fluctuating temperatures and moisture. Without protection, they can only last a few months. And because their solar capabilities are a relatively new discovery, their efficiency still lacks behind the commercially available silicon-based cells. However, perovskite solar cells have the highest power to weight ratio amongst viable photovoltaic technologies.
The team led by Senior Research Fellow at the Australian Centre for Advanced Photovoltaics (ACAP), Anita Ho-Baillie, announced a 16 square cm perovskite solar cell with a 12.1% efficiency rating: the largest single perovskite photovoltaic cell certified with the highest energy conversion efficiency.
International testing Centre Newport Corp, based in Montana, independently verified this record efficiency.
Other achievements of the UNSW team include an 18% efficiency rating on a 1.2 square cm single perovskite cell, and an 11.5% for a 16 square cm four-cell perovskite mini-module, both also independently certified by Newport.
"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%, and have since grown in leaps and bounds. These results place UNSW among the best groups in the world producing state-of-the-art high performance perovskite solar cells. And I think we can get to 24% within a year or so."
In addition to improving efficiency, the UNSW team is also working on extending the durability of perovskite cells. Even so, there are many existing applications where even disposable low-cost, high-efficiency solar cells could be attractive, such as use in disaster response, device charging and lighting in electricity-poor regions of the world.
[Dr Anita Ho-Baillie with the perovskite solar cell. Photo: UNSW]