CdSe nanoplatelets (NPLs), otherwise known as quantum wells, are 2D luminescent colloidal nanomaterials with well-defined thickness-tunable opto-electronic features with ultranarrow bandwidths. Besides being a promising material for white light LED (w-LED) applications, ion exchange potentially enables design of new complex structures including metastable phased nanoparticles (NPs). In our study, we explore the cation exchange (CE) transformations in three different NPLs distinguished primarily by the number of atomic layers of Cd and Se (7, 9 11 in total) along the thickness direction using copper (Cu<sup>+, 2+</sup>) as the substituting ions. The extent of completion and kinetics of CE (in the earlier intermediates) were found to be dependent on the number of atomic layers and the copper precursors. Furthermore, structural investigation yields the absence of any alloyed stages leading to conversion to Cu<sub>2-x</sub>Se domains in the NPLs. The cation exchange is followed using ensemble absorption and photoluminescence, which are then studied using electron microscopy techniques, and XRD analyses. Using density functional theory calculations and mapping of the ion exchange phase space in this study, we aim to advance towards the high-throughput experimentations in this system using uncommon ions selected through AI-assisted predictive framework.

Ion exchange pathways in CdSe nanoplatelets: Combined experimental and theoretical investigations

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