Preventing lead leakage in perovskite solar cells with a sustainable titanium dioxide sponge

As the market uptake of perovskite solar cells (PSCs) is projected to grow rapidly, this clean energy technology will play an increasingly important role in reducing the global carbon footprint. However, one of the major barriers to its full commercialization is the presence of toxic lead (Pb), which enables the current record in photoconversion efficiency but risks being released into the environment when subjected to water or rain. Here we show that Pb leakage can be prevented by applying a transparent titanium dioxide (TiO2) sponge that allows for an efficient Pb sequestration of 58 ng cm(-2) nm(-1). Already an essential material for PSCs, the additional use of TiO2 through a scalable and solvent-free sputtering process promises extra cost benefits and higher sustainability. Further demonstration of the sponge application with desired thickness on ready-to-use devices, glass and polymeric foils enforces the practical value of the current approach. Our study provides a sustainable solution to one of the environmental and health risks of PSCs and would accelerate their practical applications.