PMC

P = 20 KPa, D = 0.4 mm, F = 4.45 mm/s, H = 0.4 mm. (a) Line shape of acute angle printing; (b) Line shape of right angle printing; (c) Line shape of obtuse angle printing; (d) Line shape of sharp angle printing; (e) Schema of overlap; (f) Double extrusion at overlap area; (g) Uniform extrusion by doubling F in the overlap area.

a, The number of papers with the terms ‘nanolithography’, ‘printing’ and ‘patterning’ in the title published each year since 1988 (searched using Thomson Scientific Web of Knowledge). Red columns correspond to the total number of papers with any of the terms ‘nanolithography’, ‘printing’ and ‘patterning’ in their titles published in all science and engineering journals. Blue columns indicate the number of papers with the terms ‘nanolithograhpy’, ‘printing’ and ‘patterning’ in their titles published in chemistry journals. The green line shows that the ratio of those papers published in chemistry journals is increasing yearly. b, Diagram dividing molecular printing by constructive and destructive methods.

DOD printing is based on one droplet jetting per one jetting trigger. To produce DOD jetting, low-viscous ink with a viscosity of approximately 10 cP should be used. The ink requirement for EHD DOD printing is similar to that of the conventional DOD inkjet, as is the EHD printing method to that of the conventional DOD inkjet. In the case of conventional inkjet printing, the raster printing technique has been widely used, because it is suitable for bitmap image printing using multi-nozzle heads. However, in the case of an EHD jet printing, there is a limit on the implementation of the multi-nozzle head due to the electrical cross-talk among nozzles. Thus, vector printing using a single nozzle is commonly used for CAD-based line printing. Nonetheless, either the raster or the vector printing mode should be selectable from the printing software to print various types of patterning. Note that the algorithm and implementation can differ according to the printing modes. In the vector mode, simultaneous movements in the x, y directions are used to print the lines, whereas, in raster printing, a single axis is used to print dots in the main direction and then move to the next swath in the sub-direction. Representative printing results using raster and vector printing are shown in .

(a) Pattern size scaling in the structured stamping (left) and intaglio transfer printing (right). QD transfer yields of the structured stamping dramatically decrease especially in high resolutions, while those of the intaglio printing approach ∼100% in all design rules. (b) Distribution of transfer printing yields at different pattern sizes (150, 75 and 45 μm). The transfer printing yield for the structured stamping dramatically decreases with the pattern size, while that of intaglio printing maintains ∼100%. Detailed results are shown in . (c) Percentile proportion of the transferred QD line pattern area to the original pattern area. As the line width decreases from 100 to 10 μm, the structured stamping yield decreases, while intaglio printing maintains ∼100%. Detailed results are shown in . (d,e) FEM simulations of the transferred area of the rectangular pattern (size: 150 × 150 μm) for the structured stamping (d) and intaglio printing (e). (f) PL image of a large-area QD dot array (7 × 7 cm) patterned by repeated aligned intaglio transfer printing on a flexible polyethylene terephthalate substrate.