Heterodimensional Interface Boosts Efficiency and Stability of Sn–Pb Perovskite Solar Cells

A analysis workforce from the Korea Advanced Institute of Science and Technology (KAIST) and Seoul National University (SNU) has achieved a major breakthrough within the efficiency and sturdiness of tin–lead (Sn–Pb) perovskite photo voltaic cells (PSCs), as reported in Small (Wiley) on January 28, 2026 (DOI: 10.1002/smll.202511627).

Sn–Pb PSCs, identified for his or her optimum low bandgap and robust potential as the underside subcell in all-perovskite tandem photo voltaic architectures, have lengthy been constrained by speedy oxidation of Sn²⁺ ions and excessive densities of defects that restrict effectivity and stability.

To overcome these challenges, the researchers developed a heterodimensional interface by incorporating FA₂SnI₆, a vacancy-ordered double perovskite (FADP) and steady n-type semiconductor, between the Sn–Pb perovskite absorber and the electron transport layer (ETL). This engineered interface successfully passivates interfacial defects, reduces non-radiative recombination, and creates improved energy-band alignment between the absorber and ETL — all of that are crucial to bettering cost extraction and general system efficiency.

Through this interfacial design, the workforce fabricated an optimized FA₀.₇MA₀.₃Sn₀.₅Pb₀.₅I₃ system that achieved a power-conversion effectivity (PCE) of 22.21%. Furthermore, the system retained 91% of its preliminary effectivity after 600 hours of storage underneath nitrogen, demonstrating considerably enhanced environmental stability in comparison with standard Sn–Pb PSCs.

These outcomes spotlight the twin profit of enhanced interfacial cost dynamics and improved materials stability, affirming the potential of vacancy-ordered double perovskites like FA₂SnI₆ as interfacial supplies in future high-performance, sturdy perovskite tandem photo voltaic cells. The research marks a notable advance in addressing key challenges for Sn–Pb PSCs and accelerates progress towards commercially viable all-perovskite tandem photovoltaics.