Tin oxide thin films were deposited by direct current （DC） reactive sputtering at gas pressures of 0.015 mbar - 0.15 mbar. The crystalline structure and surface morphology of the prepared SnO2 films were introduced ...Tin oxide thin films were deposited by direct current （DC） reactive sputtering at gas pressures of 0.015 mbar - 0.15 mbar. The crystalline structure and surface morphology of the prepared SnO2 films were introduced by X-ray diffraction （XRD） and atomic force microscopy （AFM）. These films showed preferred orientation in the （110） plane. Due to AFM micrographs, the grain size increased non-uniformly as the working gas pressure increased.展开更多
This paper reports a new donor-acceptor copolymer semiconductor, PTBTh, comprising bithiophene and bithiazole where the regular coplanar structure and the intramolecular charge transfer are expected to increase the op...This paper reports a new donor-acceptor copolymer semiconductor, PTBTh, comprising bithiophene and bithiazole where the regular coplanar structure and the intramolecular charge transfer are expected to increase the opportunity for --- stacking and charge transport. The AFM image shows lamellar stacking of the polymer on the surface. The field-effect transistor (FET) properties of PTBTh have been evaluated by a bottom-contact/bottom-gate TFT configuration. The device showed a high hole mobility of 1.14×10-2 cm2 V-1 s-1 and a current on/off ratio of 3×105 with the polymer thin film annealed at a mild temperature of 120 ℃ when measured under ambient conditions.展开更多
Thin films of block copolymers （BCPs） are widely accepted as potentially important materials in a host of technological applications including nano- lithography. In order to induce domain separation and form well-de...Thin films of block copolymers （BCPs） are widely accepted as potentially important materials in a host of technological applications including nano- lithography. In order to induce domain separation and form well-defined structural arrangements, many of these are solvent-annealed （i.e. solvent swollen） at moderate temperatures. The use of solvents can be challenging in industry from an environmental point of view as well as having practical/cost issues. However, a simple and environmentally friendly alternative to solvo-thermal annealing for the periodically ordered nanoscale phase separated structures is described herein. Various asymmetric polystyrene-b-poly（ethylene oxide） （PS-b-PEO） thin films were annealed in a compressible fluid, supercritical carbon dioxide （scCO2）, to control nanodomain orientation and surface morphologies. For the first time, periodic well defined, hexagonally ordered films with sub-25 nm pitch size were demonstrated using a supercritical fluid （SCF） process at low temperatures and pressures. Predominant swelling of PEO domains in scCO2 induces nanophase separation, scCO2 serves as green alternative to the conventional organic solvents for the phase segregation of BCPs with complete elimination of any residual solvent in the patterned film. The depressurization rate of scCO2 following annealing was found to affect the morphology of the films. The supercritical annealing conditions could be used to define nanoporous analogues of the microphase separated films without additional processing, providing a one-step route to membrane like structures without affecting the ordered surface phase segregated structure. An understanding of the BCP self- assembly mechanism can be realized in terms of the deviation in glass transition temperature, melting point, viscosity, interaction parameter and volume fraction of the constituent blocks in the scCO2 environment.展开更多
文摘Tin oxide thin films were deposited by direct current （DC） reactive sputtering at gas pressures of 0.015 mbar - 0.15 mbar. The crystalline structure and surface morphology of the prepared SnO2 films were introduced by X-ray diffraction （XRD） and atomic force microscopy （AFM）. These films showed preferred orientation in the （110） plane. Due to AFM micrographs, the grain size increased non-uniformly as the working gas pressure increased.
基金supported by the National Natural Science Foundation of China (20772094)
文摘This paper reports a new donor-acceptor copolymer semiconductor, PTBTh, comprising bithiophene and bithiazole where the regular coplanar structure and the intramolecular charge transfer are expected to increase the opportunity for --- stacking and charge transport. The AFM image shows lamellar stacking of the polymer on the surface. The field-effect transistor (FET) properties of PTBTh have been evaluated by a bottom-contact/bottom-gate TFT configuration. The device showed a high hole mobility of 1.14×10-2 cm2 V-1 s-1 and a current on/off ratio of 3×105 with the polymer thin film annealed at a mild temperature of 120 ℃ when measured under ambient conditions.
文摘Thin films of block copolymers （BCPs） are widely accepted as potentially important materials in a host of technological applications including nano- lithography. In order to induce domain separation and form well-defined structural arrangements, many of these are solvent-annealed （i.e. solvent swollen） at moderate temperatures. The use of solvents can be challenging in industry from an environmental point of view as well as having practical/cost issues. However, a simple and environmentally friendly alternative to solvo-thermal annealing for the periodically ordered nanoscale phase separated structures is described herein. Various asymmetric polystyrene-b-poly（ethylene oxide） （PS-b-PEO） thin films were annealed in a compressible fluid, supercritical carbon dioxide （scCO2）, to control nanodomain orientation and surface morphologies. For the first time, periodic well defined, hexagonally ordered films with sub-25 nm pitch size were demonstrated using a supercritical fluid （SCF） process at low temperatures and pressures. Predominant swelling of PEO domains in scCO2 induces nanophase separation, scCO2 serves as green alternative to the conventional organic solvents for the phase segregation of BCPs with complete elimination of any residual solvent in the patterned film. The depressurization rate of scCO2 following annealing was found to affect the morphology of the films. The supercritical annealing conditions could be used to define nanoporous analogues of the microphase separated films without additional processing, providing a one-step route to membrane like structures without affecting the ordered surface phase segregated structure. An understanding of the BCP self- assembly mechanism can be realized in terms of the deviation in glass transition temperature, melting point, viscosity, interaction parameter and volume fraction of the constituent blocks in the scCO2 environment.
