Controlled assembly of perovskite nanoparticles by photoswitchable functional ligands

Organic ligands play a crucial role in the properties and functionality of nanostructures. Functional ligands are an interesting research direction that can be utilized to influence the properties and functionality of nanoparticles (NPs). In this work, we demonstrate controlled assembly of CsPbBr3 perovskite NPs as a result of light. Azobenzene derivative molecules were used as the photoswitchable ligands for the NPs. The assembly and disassembly of the NPs were achieved by cis–trans isomerization. By utilizing polarization-modulated, infrared reflection–absorption spectroscopy and diffusion-ordered nuclear magnetic resonance, we were able to track the attachment of the ligands to the surface of the NPs. Absorbance, photoluminescence and high-resolution, transmission electron microscopy followed the assembly and disassembly of the NPs. This work demonstrates functional ligands paired to perovskite nanostructures through controlling their assembly and disassembly, which opens the way for sensing and photodetection applications.