Morphology enhancement of self-assembled CH3NH3PbI3 nanoparticles through customized solvent evaporation temperatures

The CH3NH3PbI3 perovskite nanoparticles are synthesized by the sonication method. It is observed that the perovskite nanoparticles are self-assembled upon solvent evaporation. Differing the drying temperatures induces different morphologies. Confirmed with the repeated experiments, a reproducible approach for acquiring enhanced morphologies and larger grain sizes is established. Perovskite nanoparticles dried at 80 degrees C had edge -less tetragonal-like shapes and samples dried at 120 degrees C possessed cubic structures with a crystalline order extending 500 nm. Whereas, solvent evaporation from iodide perovskite dried at room temperature did not yield any ordered morphology. Self-assembled nanostructures showed anisotropic photoluminescence emission that confirms ordered assembly of the structures. Perovskites dried at 80 degrees C had the highest degree of photo-luminescence emission polarization, which is due to their anisotropic micro-crystalline structure. According to FTIR results, the interaction of methylammonium cation with PbI cage in lead iodide perovskites is influenced by temperature treatments, leading to altered crystalline structure and hence diverse morphologies. Furthermore, all of the self-assembled perovskites were highly photo luminescent with slight red-shifts in samples dried at higher temperatures. We also observed up-conversion emission with a 1064 nm excitation, which confirms the existence of nonlinear response in these perovskite structures.

Automated summary

CH3NH3PbI3 perovskite nanoparticles were synthesized using the sonication method and self-assembled upon solvent evaporation. Different drying temperatures resulted in different morphologies, with the highest degree of photo-luminescence emission polarization observed at 80°C. The interaction of methylammonium cation with PbI cage in lead iodide perovskites was influenced by temperature treatments, leading to altered crystalline structure and diverse morphologies.