Researchers at OIST (Okinawa Institute of Science and Technology) have been investigating the cause of rapid degradation of perovskite solar cells. Their conclusions suggested that the degradation of MAPbI3 perovskites may not be a fixable issue, since iodide-based perovskites produce a gaseous form of iodine, I2, during operation, which in turn causes further degradation of perovskite.

In contrary to many researchers that have pointed to external sources (like moisture, atmospheric oxygen and heat) as the cause of MAPbI3 degradation, the fact that these solar cells continue to degrade even in the absence of these factors led the OIST team to believe that a property intrinsic to these cells was causing the breakdown of material.

Scientists at Imperial College London have conducted experiments to follow the direction in which electrons move in perovskite solar cells when they are generated with a short pulse of light. They found that the mobile charged defects are still present even in solar cells with very efficient contact materials, despite these cells showing no hysteresis. Hysteresis was only found when cells suffered the combined effects of both the defects and poor selectivity at the contacts.

perovskite films contain charged defects that tend to impair their performance. Slow movement of these defects is thought to be responsible for a process known as hysteresis, which leads to irregularities in the efficiency with which light is converted to electrical current. Light-generated electricity exits the solar cell in the form of electrons to be harnessed. This is done via ‘contacts’ that sandwich the light-absorbing film. Previously, scientists have managed to address hysteresis by using more ‘selective’ contact materials that ensure a one-way flow of electrons out of the solar cell.

2016 is soon over - and it was another exciting year for the perovskite industry. Researchers continue to innovate and develop more efficient solar panels, and it seems that commercialization of perovskite solar panels is approaching.

Here are the top 10 stories posted on Perovskite-Info in 2016, ranked by popularity (i.e. how many people read the story):

1. Breakthrough reproducibility achieved for perovskite solar cells (Mar 21)
2. Perovskite-silicon tandem solar cells reach 25.5% efficiency (Apr 13)
3. Semi-transparent perovskite PV modules created by imec (Jun 1)
4. EPFL team creates low-cost hole-transport material that improves efficiency of perovskite solar cells (Jan 20)
5. A new electron transport layer increase power conversion efficiency in perovskite solar cells (Jan 5)
6. Flexible perovskite-perovskite solar cells reach 21.7% efficiency (Nov 9)
7. Dyesol gets ready to launch a Major Area Demonstration Prototype for its perovskite PV technology (Feb 8)
8. Spray-on perovskite solar cells close to commercialization (Aug 7)
9. Water-resistant perovskite solar cell maintains efficiency (Jan 25)
10. Graphene-perovskite solar cells exceed 18% efficiency (Oct 5)