Scalable fabrication of methylammonium‑free wide‑bandgap perovskite solar cells by blade coating in ambient air

Wide-band-gap perovskites are the key top-cell for >30 % tandem modules, yet spin-coating and methylammonium (MA) instability block factory-scale production. Now researchers from Southwest Petroleum University, UNSW and UCL have formulated an MA-free ink that can be blade-coated in ambient air and delivers certified 23 % efficiency—one of the highest values ever reported for a 1.69 eV MA-free film.

Why This Matters

• Air-processable: 23 % small-area cell and 20.2 % 10.5 cm² mini-module fabricated entirely in room air—no glove-box.
• MA-free stability: eliminates MA cation de-protonation and proton migration, extending operational lifetime (80 % PCE retained after 320 h MPP tracking at 45 °C).
• Factory friendly: blade-coating + vacuum-quench compatible with metre-wide roll-to-roll lines and existing tandem equipment.

Innovative Design & Features

• RbI + Pb(SCN)₂ synergy: Rb ions segregate to grain boundaries, suppress PbI₂ precipitation while preserving micron-scale grains; Pb(SCN)₂ slows nucleation for compact, low-defect films.
• Intermediate-phase control: 2-imidazolidinone additive stabilises a metastable solvate that converts to pure α-phase perovskite during 120 °C anneal.
• Graded interface: PEAI/EDAI₂ surface layer plus Al₂O₃ nano-sheet scaffold minimise non-radiative recombination and push V_OC to 1.26 V.

Applications & Future Outlook

• Tandem ready: band-gap (1.69 eV) and current density (21.75 mA cm^-2) matched to c-Si bottom cells; modules retain 92 % PCE after 1,100 h ambient storage.
• Upscaling roadmap: uniform 5 × 5 cm² films verified by XRD mapping; laser-patterned mini-modules show negligible area loss (fill factor 76 %).
• Industry impact: simple, low-temperature process shortens the efficiency-cost-stability gap for perovskite/silicon tandems and accelerates gigawatt-scale manufacturing.

This work offers a clear, additive-guided pathway to print stable, high-performance wide-band-gap layers under factory air—bringing low-cost, high-efficiency tandem photovoltaics one step closer to market deployment.