One of the persistent challenges holding back perovskite solar cells lies in the way their hole transport layers (HTLs) are prepared. Traditionally, organic semiconductors like Spiro-OMeTAD or PTAA are “doped” using additives such as lithium bis(trifluoromethane)sulfonimide (LiTFSI). While the process works, it’s far from ideal: it depends on a slow and unpredictable oxidation reaction in air, while the leftover lithium ions become a hidden culprit of long‑term instability, drifting inside the device and eventually degrading performance.
To overcome these drawbacks, researchers from North China Electric Power University and Beijing Huairou Laboratory developed a new strategy they called electrolysis doping. Instead of relying on ambient chemistry, they directly apply an electrical bias that allows the semiconductor to be oxidized in a clean, controlled way on the anode surface. At the same time, the excess lithium ions are reduced at the cathode and effectively removed. The result is a dual benefit — a precisely doped organic semiconductor and the elimination of the mobile ions that undermine stability.
When integrated into perovskite solar cells, the impact is impressive. Using electrolyzed Spiro in a regular n–i–p structure, the devices achieved a power conversion efficiency of 26.16%. In an inverted architecture with electrolyzed PTAA, they reached 25.57%. And just as importantly, these devices proved impressively stable, retaining over 90% of their initial efficiency even after 1,400 hours under continuous one‑sun illumination.
By simplifying the doping process and at the same time solving the lithium problem, electrolysis doping offers both higher performance and greater reliability. It represents a significant advance toward making perovskite solar cells not just record‑setting in the lab, but practical and stable enough for real‑world deployment.
