Stable comprehensive dopants for efficient and scalable perovskite solar cells

Controlled doping of organic semiconductors is crucial for their application in optoelectronic devices. In perovskite solar cells (PSCs), breakthrough efficiencies have relied on doped Spiro-OMeTAD hole transport materials. However, the ubiquitous adoption of multicomponent lithium-based doping schemes, known for their hygroscopic, volatile, and temperamental nature, remains a major issue for n-i-p PSCs. Therefore, next-generation dopants must be re-engineered from first principles. Here, we report a class of tailored ferrocenium oxidants as high-performance, comprehensive Spiro-OMeTAD dopants. Tuning ferrocenium reduction potentials enables near-quantitative Spiro-OMeTAD ⋅+ conversion, affording optimal electronic and energetic properties. The resulting ferrocenium-doped PSCs outperform conventional counterparts, achieving device and module efficiencies of 26.13% and 22.21%, respectively, with ultra-low dopant loadings. Devices show excellent operational stability, retaining 95% (unheated) and 87% (held at 65°C) of the initial efficiency after 1,000 h of continuous operation. Our results reveal the unrecognized potential of comprehensive doping paradigms in PSCs and beyond.