Researchers at the University of Colorado Boulder and NREL have uncovered the reason, microscopic defects that turn into heat-trapping hotspots, threatening to short-circuit the next generation of solar tech.
Scientists have finally cracked one of the key reliability issues plaguing the next-generation solar tech based on perovskite. Researchers at University of Colorado Boulder and the National Renewable Energy Laboratory (NREL) have revealed that microscopic defects in perovskite solar cells trigger a reverse-bias breakdown that leads to overheating and what looks like “melting” of the material.
In practical terms, when part of a solar panel is shaded or otherwise obstructed, the affected cell can flip into reverse bias: the current from the still-active cells pushes through it in the wrong direction, generating heat. In conventional silicon panels, engineers circumvent this with bypass diodes that route around the weak point. But perovskite cells haven’t had that luxury—they’re too weak, in part because their processing introduces tiny pinholes and thinner spots.
Using a battery of high-resolution methods — electroluminescence imaging, scanning electron microscopy, laser-scanning confocal microscopy and video thermography — the team observed how and where failure starts. They discovered that defects in the perovskite film act as hotspots under reverse bias, rapidly heating up and essentially shorting across the contact layers. Cells that were defect-free survived hours of reverse bias without significant damage.
The root cause lies in the film formation itself. Perovskite layers are made via solution processing: a low-viscosity precursor is dropped and dried to form a film, but this can leave pinholes and gaps—especially in larger-scale devices. Those imperfections become the weak link under stress.
The implications are clear: to make perovskite solar cells viable for real-world, large-scale deployment, manufacturers must push toward pinhole-free films and robust contact layers that avoid reverse-bias failure. This insight moves the technology a step closer to commercialization, but it also underscores the importance of high-precision processing and quality control in emerging energy materials. The mystery of why perovskite solar cells “melt” isn’t some exotic chemical reaction—it’s simply that tiny defects act like ticking bombs under reverse current, and now we know how to look for them.
