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Graphene fiber. ← GO solution in glass pipeline (0.4mm) Drying solution at 230°C ↓ (left) ~30µm graphene fiber was obtained (right) Graphene nanosheets are aligned. Graphene fiber. ← Electrical conductivity was not degraded after bending at r~2mm
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Graphene fiber ← GO solution in glass pipeline (0.4mm) Drying solution at 230°C ↓ (left) ~30µm graphene fiber was obtained (right) Graphenenanosheets are aligned
Graphene fiber ← Electrical conductivity was not degraded after bending at r~2mm Useful for wearable and flexible electronics ← Properties can be tuned by introducing nanoparticles in fiber (ex) Ferromagnetism by iron oxide NP Photocurrent can be obtained by TiO2 NP
Graphene fiber Merit of graphene fiber – inexpensive graphene, strong fiber (Left) conventional solution-spinning method and mechanical property of graphene fiber (Bottom right) mechanical property of graphene fiber obtained by glass pipeline method
Graphene fiber Possible applications By means of flexible and wearble electronics, Photovoltaic and Piezoelectric energy harvesting can be considered
Nanosheet dielectric Mica as a gate dielectric Free standing mica (2006) Exfoliated mica on 3M tape (2011) Exfoliation of mica Au evap. Pentacene evap. Pentacene (evaporation) Mica sheet (1µm) Au (evaporation) Au evap. Exfoliation of mica CuPc evap. CuPc(evaporation) Mica sheet (100nm) Au (evaporation) 3M tape
Nanosheet dielectric (left) exfolitaed mica flakes Method: Exfolitaion with 3M tape Dissolve tape in acetone Acetone and sheets are filtered Drying Objects for future works Chemical exfolitation Dispersion Deposition of transfer
Sol-gel dielectric Performance uniformity problem: Use of MEA : Powder precipitation problem
Sol-gel dielectric Without stabilizer, solution was dissolved at 50°C Performance (leakage current) was degraded Films were tend to be dewet on substrate surface
Sol-gel dielectric EG was used for improving spin-coating (Left) Failed experiment due to high resistivity of Si waver (Right) Leakage current density of sol-gel zirconatess
Sol-gel dielectric Future works Exfoliation: Introducing larger ions (No reference for mica) TBA+ Intercalation agent: ex) TBAH or PA Solution pH Hydrothermal or AP Etc… Chemical composition of mica X2Y4–6Z8O20(OH,F)4 in which X is K, Na, or Ca or less commonly Ba, Rb, or Cs; Y is Al, Mg, or Fe or less commonly Mn, Cr, Ti, Li, etc.; Z is chiefly Si or Al, but also may include Fe3+ or Ti.