To anyone who has spent some time in photovoltaic (PV) power circles, the word ‘perovskite’ probably sounds familiar. Offering arguably better bandgap properties than traditional silicon cells, perovskite-based PV panels also promise to be cheaper and (literally) more flexible, but commercialization has been elusive. This is something which Oxford PV seeks to change, with the claim that they will be shipping the first hybrid perovskite-silicon panels to a US customer.
Although Oxford PV prefers to keep the details of their technology classified, there have been decades of research on pure perovskite PV cells as well as tandem perovskite-silicon versions. The reason for the tandem (i.e. stacked) construction is to use more of the solar rays’ spectrum and total energy to increase output. The obvious disadvantage of this approach is that you need to find ways to make each layer integrate in a stable fashion, with ideally the connecting electrodes being transparent. A good primer on the topic is found in this 2021 review article by [Yuanhang Cheng] and [Liming Ding].
The primary disadvantage of perovskites has always been their lack of longevity, with humidity, UV irradiation, temperature and other environmental factors conspiring against their continued existence. In a 2022 study by [Jiang Liu] et al. in Science it was reported that a perovskite-silicon tandem solar cell lost about 5% of its initial performance after 1,000 hours. A 2024 study by [Yongbin Jin] et al. in Advanced Materials measured a loss of 2% after approximately the same timespan. At a loss of 2%/1,000 hours, the perovskite layer would be at 50% of its initial output after 25,000 hours, or a hair over 2.85 years.
A quick glance through the Oxford PV website didn’t reveal any datasheets or other technical information which might elucidate the true loss rate, so it would seem that we’ll have to wait a while longer on real data to see whether this plucky little startup has truly cracked the perovskite stability issue.
Top image: Summary of tandem perovskite-silicon solar cell workings. (Credit: Yuanhang Cheng, Liming Ding, SusMat, 2021)