3 research outputs found
Microchannel Wetting for Controllable Patterning and Alignment of Silver Nanowire with High Resolution
Patterning
and alignment of conductive nanowires are essential for good electrical
isolation and high conductivity in various applications. Herein a
facile bottom-up, additive technique is developed to pattern and align
silver nanowires (AgNWs) by manipulating wetting of dispersions in
microchannels. By forming hydrophobic/hydrophilic micropatterns down
to 8 μm with fluoropolymer (Cytop) and SiO<sub>2</sub>, the
aqueous AgNW dispersions with the optimized surface tension and viscosity
self-assemble into microdroplets and then dry to form anisotropic
AgNW networks. The alignment degree characterized by the full width
at half-maximum (FWHM) can be well-controlled from 39.8° to 84.1°
by changing the width of microchannels. A mechanism is proposed and
validated by statistical analysis on AgNW alignment, and a static
model is proposed to guide the patterning of general NWs. The alignment
reduced well the electrical resistivity of AgNW networks by a factor
of 5 because of the formation of efficient percolation path for carrier
conduction
Microchannel Wetting for Controllable Patterning and Alignment of Silver Nanowire with High Resolution
Patterning
and alignment of conductive nanowires are essential for good electrical
isolation and high conductivity in various applications. Herein a
facile bottom-up, additive technique is developed to pattern and align
silver nanowires (AgNWs) by manipulating wetting of dispersions in
microchannels. By forming hydrophobic/hydrophilic micropatterns down
to 8 μm with fluoropolymer (Cytop) and SiO<sub>2</sub>, the
aqueous AgNW dispersions with the optimized surface tension and viscosity
self-assemble into microdroplets and then dry to form anisotropic
AgNW networks. The alignment degree characterized by the full width
at half-maximum (FWHM) can be well-controlled from 39.8° to 84.1°
by changing the width of microchannels. A mechanism is proposed and
validated by statistical analysis on AgNW alignment, and a static
model is proposed to guide the patterning of general NWs. The alignment
reduced well the electrical resistivity of AgNW networks by a factor
of 5 because of the formation of efficient percolation path for carrier
conduction
Non-antireflective Scheme for Efficiency Enhancement of Cu(In,Ga)Se<sub>2</sub> Nanotip Array Solar Cells
We present systematic works in characterization of CIGS nanotip arrays (CIGS NTRs). CIGS NTRs are obtained by a one-step ion-milling process by a direct-sputtering process of CIGS thin films (CIGS TF) without a postselenization process. At the surface of CIGS NTRs, a region extending to 100 nm in depth with a lower copper concentration compared to that of CIGS TF has been discovered. After KCN washing, removal of secondary phases can be achieved and a layer with abundant copper vacancy (V<sub>Cu</sub>) was left. Such compositional changes can be a benefit for a CIGS solar cell by promoting formation of Cd-occupied Cu sites (Cd<sub>Cu</sub>) at the CdS/CIGS interface and creates a type-inversion layer to enhance interface passivation and carrier extraction. The raised V<sub>Cu</sub> concentration and enhanced Cd diffusion in CIGS NTRs have been verified by energy dispersive spectrometry. Strengthened adhesion of Al:ZnO (AZO) thin film on CIGS NTRs capped with CdS has also been observed in SEM images and can explain the suppressed series resistance of the device with CIGS NTRs. Those improvements in electrical characteristics are the main factors for efficiency enhancement rather than antireflection