Polyvinylpyrrolidone adhesion layer for increased uniformity and optical transmittance of silica nanoparticle antireflective coatings

Abstract

The uniformity of silica nanoparticle antireflective coatings deposited from aqueous solutions on glass substrates is limited by the high surface tension and low evaporation rate of water. In this work, thin films of polyvinylpyrrolidone (PVP) were utilized as an adhesion layer to increase the uniformity and optical transmittance of silica nanoparticle coatings. The increase in adhesive force caused by the presence of the PVP layer was measured using atomic force microscopy (AFM). The micro- and nanoscale uniformities of silica nanoparticle films with and without PVP adhesion layers were characterized using scanning electron microscopy and AFM. It was found that a thin PVP adhesion layer provides the adhesion required to form uniform films of silica nanoparticles. Solar weighted transmittance of 97.6% over a wavelength range of 330–1000 nm was achieved with soda-lime glass substrates coated on both sides.

Keywords:

• silica nanoparticles
• adhesion layer
• polyvinylpyrrolidone
• antireflective coating
• nanoscale adhesion force measurement

Acknowledgments

The authors thank Robert Fleming for technical discussions related to this paper. The authors also thank the Electron Optics Facility (EOF) of the University of Arkansas for equipment use. Support from the National Science Foundation (NSF) under grant numbers EPS-1003970 and CMS-0645040 is gratefully acknowledged.