The vast promise of perovskite material as a solar semiconductor has resulted in a rush of research within the academic community and efforts to develop commercial applications for the technology from a number of startup and established solar companies. The stability of the perovskite layer has been a major hurdle to its commercialization, however new research from the UCLA points to an innovative solution.
A research group lead by Yang Yang, from the California NanoSystems Institute has develop a method by which the perovskite semiconductor is placed between two metal oxide layers in a method that does not overly affect conversion efficiency and greatly enhances durability.
Pervoskites are extremely sensitive to rapid degradation when exposed to air and are particularly sensitive to water. By protecting the perovskite layer with the metal oxide, Yang was able to increase the cells life in open-air storage at room temperature for 60 days. The pervoskites conversion efficiency, of 14.8% at the outset, only decreased by 10% in that period.
A control device, without the metal oxide sandwich and instead using an organic transport layer, degraded completely within five days.
Importantly the metal oxide layer did not prevent the transport of electrons from the perovskite. The metal oxide acted as electron hole transporting layer in the UCLA device.
So far stability is one of the major issues in perovskite solar cells, noted technology analysts IDTechEx Research. Successfully tackling this issue may unlock perovskite solar cells as a game-changer.
The efficiency improvements exhibited by pervoskites has been unparalleled in recent years. Yang Yang told the UCLA newsroom that its team has increased conversion efficiency from less than 1% to close to 20% in two years in results not dissimilar to those achived by researchers elsewhere.
There has been much optimism about perovskite solar cell technology, said Yang Yang. But its short lifespan was a limiting factor we have been trying to improve on since developing perovskite cells with high efficiency.
The UCLA teams results were published last month in the Nature Nanotechnology journal.