Lead Powder Delivers 24% Durable Sn–Pb Perovskites

• Tin–lead perovskite hits 24.07% without SnF2: metallic lead + PbF2 boost crystallization and stability, retaining 60% output after 550h at 85°C—tandem-ready durability reported in Nature Communications.

Researchers at East China Normal University and Linköping University report a tin–lead perovskite solar cell reaching 24.07% efficiency, up from 16.43% in SnF2-based controls, in Nature Communications. They eliminate tin fluoride—implicated in photothermal instability and electrode corrosion—and instead add metallic lead powder to regulate crystallization, plus a PbF2 surface passivation.

The planar ITO/P3CT-Cs/perovskite/PbF2/C60/BCP/LiF/Cu devices held about 60% of initial output after 550 hours at 85°C under maximum power tracking, outperforming SnF2 devices that corroded Cu and ITO even at room temperature. The chemistry lowers trap density, curbs higher-valent tin, and advances durable low-bandgap absorbers for all-perovskite tandems and future deployment.

How does SnF2-free chemistry with Pb powder and PbF2 raise efficiency and stability?

• Eliminates bulk fluoride additive: Removing SnF2 avoids mobile F− in the absorber that can migrate under bias/heat, generate corrosive species, and catalyze etching of Cu/ITO, directly improving operational stability.
  
• Metallic Pb as a redox buffer: Pb^0 consumes oxidants and reduces Sn4+ back to Sn2+, suppressing self-doping and deep traps linked to Sn vacancies, which lifts Voc and cuts nonradiative loss.
  
• Controlled crystallization: Dispersed Pb seeds regulate nucleation and growth, yielding larger, denser grains with fewer grain boundaries; this increases carrier lifetime, raises FF, and reduces hysteresis.
  
• Defect chemistry tuning: The Pb-assisted growth curbs halide/metal vacancy formation, narrowing Urbach tails and improving band-edge sharpness for higher Jsc and Voc.
  
• PbF2 surface passivation: Strong Pb–F bonds neutralize undercoordinated sites at the top surface, lowering surface recombination velocity and boosting quasi-Fermi level splitting.
  
• Interfacial barrier function: The thin PbF2 layer blocks halide and metal ion interdiffusion, mitigating reactions with C60/Cu and ITO and preventing contact corrosion and shunting.
• Thermal/photochemical robustness: With fewer mobile ions and stabilized Sn2+, the film resists phase drift and decomposition under light and heat, sustaining MPP at elevated temperature.