Free Standing Nanocrystal Thin Films

Summary

Vanderbilt researchers have developed a process that creates free standing nanocrystalline thin films using a simple, robust and cost- efficient process. This paves the way for manufacturing conformal films of nanocrystals at a fraction of the cost as compared to techniques currently used. The process could be applied in the manufacture of a number of end products such as solar cells supercapacitors, magnetic storage, semiconductor devices and catalysis.

Electrophoretic deposition is utilized to fabricate free standing nanocrystal- line thin films. This robust deposition process has the following unique combination of characteristics:

• The nanocrystalline films can be comprised of any metallic, semicon- ducting, or insulating nanocrystal or nanoparticle.

• The nanocrystalline films contain no residual chemical cross linkers or cross-linking agents.

• No user-added nanocrystal binding mediators are added to the nano- crystals prior to, during or after the deposition.

• The nanocrystalline films onlyconsist of the core nanocrystals, their growth-terminating, aggregation sup- pressing surface ligands, and air.

The resulting nanocrystalline films possess a unique set of physical and structural characteristics:

• The nanocrystalline films are comprised only of the individual constituent nanocrystal building blocks.

• The deposition technique allows for the production of films with macroscopic lateral dimensions and up to mesoscopic thicknesses (upwards of 1.0 microns).

• The nanocrystalline films are free- standing, without a supportive matrix, provided by another material.

• The thickness of the nanocrystalline films are governed by particle-particle interactions, such as van der Waals, steric, Coulombic, dipole-dipole, and other interactions.

• The nanocrystalline films can be detached from the original deposition site and can be deployed elsewhere.

• The nanocrystalline films are flexible and can conform to coat surfaces with virtually any contour.

One alternative technique to electrophoretic deposition (EPD) is called layer-by-layer (LbL) assembly. Although EPD has more attractive features, LbL is more widely used in nanoparticle assembly and has more than EPD does. Given the wide range of applications, it is difficult to estimate the potential revenue that this technology might produce. However, nanotechnology products across all sectors currently comprise a growth market, with a market size in 2003 of $499 million and an estimated market size of $4.5 billion in 2009. If successfully commercialized, it is anticipated that this technology will facilitate and accelerate the growth of the nanotechnology product market.

Vanderbilt seeks a commercial partner to prove the technology on a larger scale and to fabricate specific devices. Lab-scale devices have been characterized and show very promising results. Since the technology can be deployed in a wide variety

of products and uses, the ideal commercialization partner will be able to channel this initial development into a high-value application. Vanderbilt researchers estimate that commercial proof of concept and viability will require approximately a year of development.

Vanderbilt University has filed a patent application with respect to the technology.