Reducing lead toxicity of perovskite solar cells with a built-in supramolecular complex

Perovskite solar cells (PSCs) as an emerging renewable energy technology are expected to play an important role in the transition to a sustainable future. However, lead toxicity of PSCs remains a major flaw hindering their large-scale implementation and compromising their sustainability, as lead is currently inevitable in making high-performance PSCs. Here we show that this can be addressed by embedding a cross-linking supramolecular complex composed of 2-hydroxypropyl β-cyclodextrin (HPβCD) and 1,2,3,4-butane tetracarboxylic acid (BTCA). The built-in HPβCD-BTCA complex can largely inhibit lead leakage from severely damaged PSCs, which retain 97% of the initial efficiency after 522 h dynamic water scouring, with only <14 ppb lead contamination in water. Toxicity evaluation implies that the chelation between HPβCD-BTCA complex and lead-bearing perovskites can also reduce the toxicity of lead-bearing PSCs to the comparable or even lower level than their lead-free counterparts. Moreover, the HPβCD-BTCA incorporation simultaneously improves the stability and reproducibility of PSCs. The proposed strategy paves a new avenue for sustainable PSCs and can move PSCs closer to commercial implementation.