Solvent-free blending of CsPbBr3 and commercial polymer: Interface-visualization, bandgap engineering and improved stability in 3D printing

•Developed solvent-free method for stable, bright CsPbBr3@polymer via extrusion.•Luminescent CsPbBr3 serves as an interface marker for studying polymer morphology.•Polymer's interpenetration enhances CsPbBr3′s green emission and halogen exchange.•CsPbBr3@PE/PLA composites suitable for integration with 3D printing. Metal halide perovskites (MHPs) encapsulated in polymer have enhanced stability and processability. Most of the MHPs/polymer composites are fabricated in organic solvents and the interaction between MHPs and polymer matrix is rarely reported. In this work, solvent-free twin-screw blending is adopted for CsPbBr3@PolymerA/PolymerB (PolymerA = polypropylene (PP), polyethylene (PE) or poly(butylene-adipate-co-terephthalate) (PBAT), PolymerB = polylactic acid (PLA)) composites preparation. Different factors including compatibilizer addition, polymer composition and CsPbBr3 feeding ratio are used to investigate the interaction between MHPs and polymer matrix. According to the wetting coefficient calculation, transmission electron microscope (TEM) and scanning electron microscope (SEM) results, CsPbBr3 is mostly distributed in the interface of PE/PLA blending. As a result, the luminescent CsPbBr3 can be used for interface marker to study the polymer interface morphology. The interpenetration morphology of polymer interface allows CsPbBr3 to show the most efficient green emission and convenient halogen exchange. Thus, the optical emission and absorption can be tuned from blue to red. PE/PLA blending endows CsPbBr3@PE5/PLA5 with 3D printing ability and improved stability against to the water, UV light and heat.