Selective templating growth of chemically inert low-dimensional interfaces for perovskite solar cells

Chemically inert low-dimensional (CI LD) halogenometallate interfaces incorporating low-reactivity bulky cations could address the trade-off between efficiency and stability in perovskite solar cells (PSCs). However, their formation is hindered by the low reactivity of their bulky cations and solubility constraints of their precursors in orthogonal solvents compatible with underlying perovskites. Here we introduce a selective templating growth strategy that leverages conventional metastable LD interfaces as templates to drive the growth of more stable CI LD interfaces through an organic cation exchange process. Our prototype PSCs achieve efficiencies of 25.1% over an active area of 1.235 cm2—among the highest reported for 1-cm2 PSCs. The PSCs retain over 93% and 98% of their initial efficiency after 1,000 h of operation and 1,100 h of thermal ageing at 85 °C, respectively. The versatility of this strategy unlocks access to CI LD interfaces, paving the way for the development of more efficient and stable PSCs.