Enhanced Photodisplacement of Perylene Bisimides via Multi-Electron Extraction from CdSe Nanoplatelets

Ligand exchange is an elegant route to tailor semiconducting nanocrystal surfaces, yet it is constrained by ground-state thermodynamics, and thus access is limited to the most stable interfacial structures. Light-driven ligand desorption, by contrast, offers a non-equilibrium handle to dynamically reconfigure surfaces and potentially reach thermodynamically inaccessible states. Here we study photoinduced displacement of perylene bisimide (PBI) ligands from 5-ML (monolayer) CdSe nanoplatelets (NPLs). Upon NPL excitation, the displacement efficiency is enhanced by up to 7 times compared with zero dimensional nanocrystals and can be tuned by NPL lateral dimensions and PBI surface loading. Time-resolved spectroscopy reveals 100-ps electron transfer from the NPL band edge to the PBI LUMO that initiates ligand dissociation. The overall yield is ultimately limited by the probability that a PBI ligand lies within the exciton diffusion range, set by vacant [100] basal-plane binding sites. These results establish nanoplatelets as efficient light-programmable platforms for dynamic ligand chemistry beyond thermodynamic control.