Ion exchange lithography: Localized ion exchange reactions for spatial patterning of perovskite semiconductors and insulators

Patterning materials with different properties in a single film is afundamental challenge and essential for the development of next-generation(opto)electronic functional components. This work introduces the concept ofion exchange lithography and demonstrates spatially controlled patterning ofelectrically insulating films and semiconductors with tunable optoelectronicproperties. In ion exchange lithography, a reactive nanoparticle “canvas” islocally converted by printing ion exchange “inks.” To demonstrate the proof ofprinciple, a canvas of insulating nanoporous lead carbonate is spatioselectivelyconverted into semiconducting lead halide perovskites by contact printing anion exchange precursor ink of methylammonium and formamidinium halides.By selecting the composition of the ink, the photoluminescence wavelength ofthe perovskite semiconductors is tunable over the entire visible spectrum. Abroad palette of conversion inks can be applied on the reactive film by printingwith customizable stamp designs, spray-painting with stencils, and paintingwith a brush to inscribe well-defined patterns with tunable optoelectronicproperties in the same canvas. Moreover, the optoelectronic properties of theconverted canvas are exploited to fabricate a green light-emitting diode (LED),demonstrating the functionality potential of ion exchange lithography