Exploring Nanoscale Structure in Perovskite Precursor Solutions Using Neutron and Light Scattering

摘要

Tailoring the solution chemistry of metal halide perovskites requires a detailed understanding of precursor aggregation and coordination.In this work,we use various scattering techniques,including dynamic light scattering(DLS),small angle neutron scattering(SANS),and spin-echo SANS(SESANS) to probe the nanostructures from 1 nm to 10 μm within two different lead-halide perovskite solution inks(MAPbI3 and a triple-cation mixed-halide perovskite).We find that DLS can misrepresent the size distribution of the colloidal dispersion and use SANS/SESANS to confirm that these perovskite solutions are mostly comprised of 1-2 nm-sized particles.We further conclude that if there are larger colloids present,their concentration must be<0.005 of the total dispersion volume.With SANS,we apply a simple fitting model for two component microemulsions(Teubner-Strey),demonstrating this as a potential method to investigate the structure,chemical composition,and colloidal stability of perovskite solutions,and we here show that MAPbI3 solutions age more drastically than triple cation solutions.