Publications by authors named "Hoseop Choi"

Three-dimensional (3D) printing has revolutionized manufacturing processes for electronics, optics, energy, robotics, bioengineering and sensing. Downscaling 3D printing will enable applications that take advantage of the properties of micro- and nanostructures. However, existing techniques for 3D nanoprinting of metals require a polymer-metal mixture, metallic salts or rheological inks, limiting the choice of material and the purity of the resulting structures.

View Article and Find Full Text PDF

In this report, we introduce a method utilizing ion-assisted aerosol lithography to stack 3D nanostructures vertically. The stacked 3D nanostructures exhibit extraordinary optical properties: the double layer 3D nanostructures show more than 5-fold increased surface enhanced Raman scattering intensities compared to their single layer counterpart. This unusual enhancement of Raman intensity implies the existence of additional vertical hotspots formed by interlayer cavity effects between the lower and upper nanostructures.

View Article and Find Full Text PDF
Article Synopsis
  • Researchers developed a three-dimensional assembly of nanoparticles to enhance light harvesting in nanocrystalline silicon thin-film solar cells.
  • The unique structuring generates multiple plasmon resonances, boosting light scattering and absorption over a broad spectrum (350-1100 nm).
  • This innovation resulted in significant efficiency gains, with a 22% increase compared to flat cells and 11% compared to cells with nanoparticle clusters, supported by simulations confirming these enhancements are due to the plasmon resonances.
View Article and Find Full Text PDF

We present an approach utilizing ion assisted aerosol lithography (IAAL) with a newly designed multi-pin spark discharge generator (SDG) for fabricating large-area three-dimensional (3D) nanoparticle-structure (NPS) arrays. The design of the multi-pin SDG allows us to uniformly construct 3D NPSs on a large area of 50 mm × 50 mm in a parallel fashion at atmospheric pressure. The ion-induced focusing capability of IAAL significantly reduces the feature size of 3D NPSs compared to that of the original pre-patterns formed on a substrate.

View Article and Find Full Text PDF

We report the effect of a nanobump assembly (NBA) constructed with molybdenum oxide (MoO3) covering Ag nanoparticles (NPs) under the active layer on the efficiency of plasmonic polymer solar cells. Here, the NPs with precisely controlled concentration and size have been generated by an atmospheric evaporation/condensation method and a differential mobility classification and then deposited on an indium tin oxide electrode via room temperature aerosol method. NBA structure is made by enclosing NPs with MoO3 layer via vacuum thermal evaporation to isolate the undulated active layer formed onto the underlying protruded NBA.

View Article and Find Full Text PDF