2 research outputs found
Uniform, Homogenous Coatings of Carbon Nanohorns on Arbitrary Substrates from Common Solvents
We demonstrate a facile technique
to electrophoretically deposit homogenous assemblies of single-walled
carbon nanohorns (CNHs) from common solvents such as acetone and water
onto nearly any substrate including insulators, dielectrics, and three-dimensional
metal foams, in many cases without the aid of surfactants. This enables
the generation of pristine film-coatings formed on time scales as
short as a few seconds and on three-dimensional templates that enable
the formation of freestanding polymer-CNH supported materials. As
electrophoretic deposition is usually only practical on conductive
electrodes, we emphasize our observation of efficient deposition on
nearly any material, including nonconductive substrates. The one-step
versatility of deposition on these materials provides the capability
to directly assemble CNH materials onto functional surfaces for a
broad range of applications. In this manner, we utilized as-deposited
CNH films as conductometric gas sensors exhibiting better sensitivity
in comparison to equivalent single-walled carbon nanotube sensors.
This gives a route toward scalable and inexpensive solution-based
processing routes to manufacture functional nanocarbon materials for
catalysis, energy, and sensing applications, among others
Perovskite Solar Cells with Near 100% Internal Quantum Efficiency Based on Large Single Crystalline Grains and Vertical Bulk Heterojunctions
Imperfections in
organometal halide perovskite films such as grain
boundaries (GBs), defects, and traps detrimentally cause significant
nonradiative recombination energy loss and decreased power conversion
efficiency (PCE) in solar cells. Here, a simple layer-by-layer fabrication
process based on air exposure followed by thermal annealing is reported
to grow perovskite films with large, single-crystal grains and vertically
oriented GBs. The hole-transport medium Spiro-OMeTAD is then infiltrated
into the GBs to form vertically aligned bulk heterojunctions. Due
to the space-charge regions in the vicinity of GBs, the nonradiative
recombination in GBs is significantly suppressed. The GBs become active
carrier collection channels. Thus, the internal quantum efficiencies
of the devices approach 100% in the visible spectrum range. The optimized
cells yield an average PCE of 16.3 ± 0.9%, comparable to the
best solution-processed perovskite devices, establishing them as important
alternatives to growing ideal single crystal thin films in the pursuit
toward theoretical maximum PCE with industrially realistic processing
techniques