Sculpting Optical Properties of Thin Film IR Filters through Nanocrystal Synthesis and Additive, Solution Processing

• Published in: Chemistry of materials 2020-10, Vol.32 (19), p.8683-8693
• Main Authors: Krivina, Raina A, Knecht, Tawney A, Crockett, Brandon M, Boettcher, Shannon W, Hutchison, James E
• Format: Article
• Language: English
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.0c03225

Plasmonic band-stop filters with tunable optical absorbance in the near- and mid-IR are important for wireless communications, bioimaging, and filtering applications. However, their design is constrained by the limited tunability of individual components and complex fabrication techniques. Here, we demonstrate a method to overcome these limitations that employs mixtures of nanocrystals to predictably sculpt the combined localized surface plasmon resonance (LSPR) for band-stop filters. The additive nature of the LSPR optical absorbances of tin-doped In2O3 (ITO) nanocrystals was used to control the combined absorbance in a nanocrystal thin film. The optical properties of the nanocrystals were modulated via a low-temperature esterification synthesis and an inexpensive solution-processing fabrication method, spin-coating, was used to produce the films. Because of the additive nature of the LSPR absorbance of the nanocrystals, the absorbance of the films can be easily predicted and designed by summing the spectra of the individual components over the range of 6000–1000 cm–1. By design and synthesis of individual nanocrystals with tailored optical properties, and selecting the right combinations of nanocrystals to incorporate into films, both wide and narrow band-stop filters were easily constructed.