Chitosan Mediated FAPbBr3 Nanocrystal Thin-Films with High Color Purity and Enhanced Hole Mobility

Composite materials which combine the advantages of both embedded constituents have been a successful strategy for developing novel multi-functional materials. Here, we demonstrate the synthesis of nanoscale materials of organic-inorganic hybrid lead halide perovskites (OIH-LHP) with enhanced optoelectronic properties and photostability by utilizing biomimetic ligand, chitosan. Notably, nanocrystals fabricated with chitosan mediated ligands exhibit an increase in photoluminescence quantum yield by 300 % and fluorescence lifetime by 1.5 times. Consequently, the lifetime distribution of the photoluminescence emission decreases to a value as low as 6 ns. More interestingly, even though chitosan is a wide band gap insulating material, its incorporation onto the perovskite NCs enhances the bulk hole mobility by at least an order of magnitude in comparison to the pristine material. With detailed spectroscopic and structural studies, we correlate these enhancements in optoelectronic parameters to the improvement in the crystal quality, phase purity, and minimized poly-dispersity of the nanocrystals. Development of such composite materials with unprecedented optoelectronic properties and outstanding stability will contribute immensely towards high performance nanocrystal devices.