AFM-IR of EHD-Printed PbS Quantum Dots: Quantifying Ligand Exchange at the Nanoscale

Lorenzo J. A. Ferraresi; Gökhan Kara; Nancy A. Burnham; Roman Furrer; Dmitry N. Dirin; Fabio La Mattina; Maksym V. Kovalenko; Michel Calame; Ivan Shorubalko

arXiv · 2401.04618

AFM-IR of EHD-Printed PbS Quantum Dots: Quantifying Ligand Exchange at the Nanoscale

Lorenzo J. A. Ferraresi·Gökhan Kara·Nancy A. Burnham·Roman Furrer·Dmitry N. Dirin·Fabio La Mattina·Maksym V. Kovalenko·Michel Calame·Ivan Shorubalko

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Abstract

Colloidal quantum dots (cQDs) recently emerged as building blocks for semiconductor materials with tuneable properties. Electro-hydrodynamic printing can be used to obtain sub-micrometre patterns of cQDs without elaborate and aggressive photolithography steps. Post-deposition ligand exchange is necessary for the introduction of new functionalities into cQD solids. However, achieving a complete bulk exchange is challenging and conventional infrared spectroscopy lacks the required spatial resolution. Infrared nanospectroscopy (AFM-IR) enables quantitative analysis of the evolution of vibrational signals and structural topography on the nano-metre scale upon ligand substitution on lead sulphide (PbS) cQDs. A solution of ethane-dithiol in acetonitrile demonstrated rapid (~60 s) and controllable exchange of approximately 90% of the ligands, encompassing structures up to ~800 nm in thickness. Prolonged exposures (>1 h) led to the degradation of the microstructures, with a systematic removal of cQDs regulated by surface-to-bulk ratios and solvent interactions. This study establishes a method for the development of devices through a combination of tuneable photoactive materials, additive manufacturing of microstructures, and their quantitative nanometre-scale analysis.

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Lorenzo J. A. Ferraresi, Gökhan Kara, Nancy A. Burnham, Roman Furrer, Dmitry N. Dirin, Fabio La Mattina, Maksym V. Kovalenko, Michel Calame, Ivan Shorubalko. 2024-01-09. AFM-IR of EHD-Printed PbS Quantum Dots: Quantifying Ligand Exchange at the Nanoscale. https://arxiv.org/abs/2401.04618

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