Researchers at the Chinese Academy of Sciences, Ningbo University, Tianjin University, PetroChina Company, Hunan Normal University, Soochow University and Ningbo New Materials Testing and Evaluation Center have developed a 3D electrical imaging technique that enables direct observation of how charge moves through perovskite films.
The team targeted a persistent challenges holding back perovskite photovoltaics: hidden internal defects that disrupt charge transport, reduce efficiency, and undermine long-term stability despite impressive lab-scale performance.
To mitigate microscopic defects that act as electrical bottlenecks, causing energy losses that conventional diagnostic tools struggle to fully capture, researchers often rely on “passivation treatments,” adding salts or organic molecules that bind to defects. But verifying how effectively these treatments work beneath the surface has remained difficult, as most techniques only probe surface layers or provide averaged electrical data.
To overcome this limitation, the team employed tomographic conductive atomic force microscopy (TC-AFM), a method that enables depth-resolved electrical mapping. The technique works by sequentially stripping ultrathin layers from a perovskite film while measuring local electrical conductivity at each depth. By stacking these measurements, the researchers reconstructed a three-dimensional map of charge transport with nanoscale resolution, offering a rare look at how electrical pathways form - and break down - inside the material.
Using this approach, the team compared untreated perovskite films with samples subjected to different passivation strategies. Untreated films exhibited extensive low-conductivity regions that hindered charge transport, particularly along grain boundaries where defects tend to accumulate. Bulk passivation treatments significantly reduced these resistive regions throughout the interior of the film. Surface passivation, meanwhile, primarily enhanced conductivity near the top interface, a critical region for electrode contact and device integration.
Films treated with both bulk and surface passivation performed best, displaying continuous and uniform conductive pathways. Remaining low-conductivity regions were largely confined to the surface, indicating a more efficient internal charge-transport network.
“These microscopic electrical characteristics are closely correlated with the resulting solar cell performance, establishing a direct link between 3D charge transport within the film and overall device efficiency,” stated Prof. XIAO Chuanxiao, a corresponding author of the study.
Beyond improving perovskite solar cells, the new imaging method offers a systems-level diagnostic tool for thin-film electronics, where internal electrical behavior often determines device reliability and lifespan.
By directly visualizing how charges migrate through complex materials, researchers can now evaluate passivation strategies with far greater precision, shifting from surface-level assumptions to data-driven material optimization. The findings could help accelerate the transition of perovskite technologies from laboratory prototypes to durable commercial devices, addressing one of the field’s most critical engineering bottlenecks. The work also opens the door to broader applications across optoelectronic and thin-film devices, where understanding internal conductivity is essential for performance and stability, according to results published in Newton.
