Nanoscale Architecture of Polymer-Organolead Halide Perovskite Films and the Effect of Polymer Chain Mobility on...

The integration of polymer chains with organolead halide perovskite (MAPbI₃) films, leading to enhanced stability and electro-optical performance, is critically affected by the molecular weight of chains. The molecular weight determines the mobility and volume of the chains, which affects the crystallization kinetics and, hence, perovskite grain size. The insulating nature of the chains is another critical factor that affects both ion migration and conduction of electronic charge. The combined effect of these factors leads to optimal performance with the use of medium-length chains. A simple model integrating the two effects accurately fits the response of the polymer-perovskite composite. Further characterization results show that the polymer-perovskite films have a three-layer architecture consisting of nanoscale polymer-rich top and bottom layers. These combined results show that the optimization of performance in polymer-perovskite devices depends critically on the size of the chains due to their multiple effects on the perovskite matrix.