Structure and performance of dielectric films based on self-assembled nanocrystals with a high dielectric constant

Abstract

Due to a typesetting error, an incorrect version of scheme 1 was published in this paper. Please see the corrected scheme 1. Abstract Self-assembled films built from nanoparticles with a high dielectric constant are attractive as a foundation for new dielectric media with increased efficiency and range of operation, due to the ability to exploit nanofabrication techniques and emergent electrical properties originating from the nanoscale. However, because the building block is a discrete one-dimensional unit, it becomes a challenge to capture potential enhancements in dielectric performance in two or three dimensions, frequently due to surface effects or the presence of discontinuities. This is a recurring theme in nanoparticle film technology when applied to the realm of thin film semiconductor and device electronics. We present the use of chemically synthesized (Ba, Sr)TiO 3 nanocrystals, and a novel deposition-polymerization technique, as a means to fabricate the dielectric layer. The effective dielectric constant of the film is tunable according to nanoparticle size, and effective film dielectric constants of up to 34 are enabled. Wide area and multilayer dielectrics of up to 8 cm 2 and 190 nF are reported, for which the building block is an 8 nm nanocrystal. We describe models for assessing dielectric performance, and distinct methods for improving the dielectric constant of a nanocrystal thin film. The approach relies on evaporatively driven assembly of perovskite nanocrystals with uniform size distributions in a tunable 7-30 nm size range, coupled with the use of low molecular weight monomer/polymer precursor chemistry that can infiltrate the porous nanocrystal thin film network post assembly. The intercrystal void space (low k dielectric volume fraction) is minimized, while simultaneously promoting intercrystal connectivity and maximizing volume fraction of the high k dielectric component. Furfuryl alcohol, which has good affinity to the surface of (Ba, Sr)

Green and scalable production of colloidal perovskite nanocrystals and transparent sols by a controlled self-collection process

“…The aggregate-free nanocrystal can also be easily incorporated into other media such as a variety of polymers, and the abundance of surface hydroxyl groups also open up a route to surface linkage with other functionalities without post-treatment with agents such as H 2 O 2 13 . In addition, in some cases monomers were used initially and later converted to polymerized forms to better prepare nanocomposites, and strong interactions between nanocrystal and the polymer have been demonstrated 14 . For instance, nanocrystal/ polymer composite thin films were fabricated by spin-coating, printing or spraying a nanocrystal/furfuryl alcohol solution in which furfural alcohol is used as a solvent as well as a monomer for poly(furfuryl) alcohol (PFA) 14 .…”

“…In addition, in some cases monomers were used initially and later converted to polymerized forms to better prepare nanocomposites, and strong interactions between nanocrystal and the polymer have been demonstrated 14 . For instance, nanocrystal/ polymer composite thin films were fabricated by spin-coating, printing or spraying a nanocrystal/furfuryl alcohol solution in which furfural alcohol is used as a solvent as well as a monomer for poly(furfuryl) alcohol (PFA) 14 . In Figure 5c, a uniform and dense BST/PFA nanocomposite thin film with high dielectric performance and good mechanical strength was prepared by printing a transparent BST nanocrystals/FA ink solution or spin (or spray) coating a BST/FA/EtOH ink solution (co-solvents FA and ethanol) followed by in-situ polymerization of FA upon heat treatment at 80 ˚C -100 ˚C (Figure 5c).…”

Highly dispersive Ba 0.6 Sr 0.4 TiO 3 nanoparticles modified P(VDF‐HFP)/PMMA composite films with improved energy storage density and efficiency

“…Fig. 4 c displays the experimental value and the fitted dielectric constant at 1 kHz using a modified Kerner model, which considers the interactions between adjacent fillers in a binary composite [40, 41]. As is shown, the experimental value coincides well with the fitted one at volume fractions <40%, then decreases sharply at high volume fraction and shows large discrepancy with the modelling, which clearly reflects the influence of pores in the composites.…”

“…As is shown, the experimental value coincides well with the fitted one at volume fractions <40%, then decreases sharply at high volume fraction and shows large discrepancy with the modelling, which clearly reflects the influence of pores in the composites. PVDF‐based polymers usually possess a high dissipation at the frequency >100 kHz [40]. The dielectric loss in Fig.…”

Manufacturing Technology (MATES) II. Task Order 0006: Air Force Technology and Industrial Base Research Sub-Task 07: Future Advances in Electronic Materials and Processes-Flexible Hybrid Electronics

“…According to the Large Area Flexible Electronics chapter in the International Electronics Manufacturing Initiative (iNEMI) 2013 Technology Roadmap, commercially available dielectric materials have permittivity values ranging from 2 to 20, but a few researchers have actually been able to achieve higher values. [220] Electrical resistivity is an intrinsic property of a material that describes how strongly the material resists the flow of electric current. [134] Because a dielectric material is designed to resist the flow of electricity and provide insulation, it is desirable for the resistivity to be as high as possible.…”