Tiny pinholes can lead to device failure in perovskite solar cells

Researchers in the United States have found microscopic pinholes in perovskites are responsible for the breakdown of such solar cells when under reverse bias conditions. They say the findings should push scientists and engineers to prioritize the production of pinhole-free films to make perovskites more robust and stable.

September 19, 2025 Patrick Jowett

Image: University of Oxford Press Office, Wikimedia Commons, CC BY 2.0

From pv magazine Global

A microscopic weak spot can lead to device failure in perovskite solar cells, according to new research.

A team of scientists in the United States has studied how a perovskite solar cell degrades when under reverse bias conditions. Their research is presented in the paper “How non-ohmic contact-layer diodes in perovskite pinholes affect abrupt low-voltage reverse-bias breakdown and destruction of solar cells,” available in the journal Joule.

The paper says lead-halide perovskites have gained traction as commercially viable solar cell materials but are still highly susceptible to abrupt breakdown and permanent degradation when subject to modest reverse bias.

The researchers used electrical measurements, electron microscopy and optical and thermal imaging to investigate abrupt breakdown and hot spotting under low reverse potentials. They deployed a before, during and after strategy to compare pictures of devices that had been exposed to reverse bias.

High-resolution images showed that microscopic pinholes in the perovskite layer cause rapid, destructive breakdown under reverse bias, despite minimally reducing power conversion efficiencies.

“Here, we confirm the role of pre-existing micrometer-scale pinholes in the solution-processed perovskite material and charge-transport layers as the primary cause of low-voltage abrupt breakdown and permanent cell degradation,” the research paper says. “That is, low-voltage abrupt breakdown in perovskite solar cells occurs around pre-existing voids, or weak spots, in the device’s layers.”

The researchers also found that thicker charge-transport layers prevent abrupt breakdown by eliminating spots where the electrodes are within nanometers of each other.

“This is an important observation, as it indicates the possibility of improving the reverse-bias stability of perovskite solar cells by improving fabrication cleanliness and uniformity, and by ensuring that the device architecture prevents highly conductive localized regions should perovskite pinholes exist,” the researchers wrote.

The findings support the argument that defects such as pinholes and thin spots in the perovskite layer are the precise location where reverse bias breakdown begins. The thermography images showed that these sites are where the material rapidly heats up and melts, essentially shorting between the two contact layers.

As a result, the research team says scientists and engineers should work to develop more robust and stable perovskite solar cells by prioritizing the production of pinhole-free films and using more robust contact layers.

“Perovskite researchers should adopt cleaner, more uniform deposition techniques to enable robust perovskites for further research and commercial applications,” the research paper adds.

Scientists from the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and Colorado’s Renewable and Sustainable Energy Institute contributed to the research.

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