Truly Low Temperature Sintering of Printed Copper Ink Using Formic Acid

Abstract

write technique that requires no masks or lithographic prepatterning of substrates and is compatible with printing manufacturing. Its drop-on-demand (DoD) technology allows the ink droplets to be deposited exactly where required on the substrate, [6] therefore minimizing material loss. Moreover, inkjet printing can be upscaled and transferred to a roll-toroll (R2R) process, [7,8] which can yield a productivity of up to 6 m 2 min −1 , while also producing small feature sizes down to 10 µm and varying shapes. [9][10][11][12] This paves the way to fully solution-processed devices, with all layers including the electrodes being deposited from an ink.The most often used ink formulations can roughly be divided into two categories: inks made from capped metal nanoparticles and metal-organic decomposition inks. [13] To prevent nozzle clogging and comply with printhead restrictions, the inks often contain low metal loading and stabilizers. A treatmentThe fabrication and feasibility of inkjet-printed electrodes for devices such as organic field-effect transistors (OFETs), highly efficient organic photovoltaics (OPVs), and high performance organic light-emitting diodes (OLEDs) underline the versatility of this printing method. [1][2][3][4][5] Inkjet printing is an additive, direct

Implementing Inkjet‐Printed Transparent Conductive Electrodes in Solution‐Processed Organic Electronics

“…When carrying out the final sintering step at 150 °C, 26% of bulk Cu conductivity was achieved on PET; with 25% bulk Cu conductivity achieved on the comparison glass substrate. At even higher temperatures the solvent evaporation and formate desorption are even more efficient, which is apparent following sintering at 230 °C on glass, whereby the high bulk Cu conductivity of 31% was reached …”

“…The OPV devices described in the previous section implement laser‐sintered Cu nanoparticle grids, which can reach limitations regarding throughput and material substrate compatibility. These limitations can be overcome by a method of postdeposition treatment and sintering of Cu ink using formic acid in a procedure that is compatible with the use of low‐cost flexible substrates with low glass transition temperatures . The additive process is chemically facile, scalable, uses minimal material and is compatible with R2R processing, thus industrially feasible, yielding structures that have excellent adhesion and stability under manual bending tests to within 2% tensile strain.…”

“…b,d,f) The developments of the C1s as well as Cu(II) and Cu(0) components of the Cu2p peak are visible in the normalized XPS spectra and corresponding depth profiles. Reproduced with permission . Copyright 2018, Wiley VCH.…”

One-pot synthesis of a stable and cost-effective silver particle-free ink for inkjet-printed flexible electronics

“…Conductive inks play a central role for printed flexible electronics since they find application in a wide range of newly-emerged electronic and energy devices. 3,4 Currently, a number of inks based on silver, [5][6][7][8][9] copper, [10][11][12][13][14][15][16] graphene, [17][18][19][20][21] carbon 22,23 and conductive polymers, [24][25][26] have been explored for printed flexible electronics. Among them, silver-based inks have been the favored metal inks because they are more costeffective than Au-based metal inks, more stable than Cu-based on inks and have better conductivity than polymer or carbonbased inks.…”

Copper micro-electrode fabrication using laser printing and laser sintering processes for on-chip antennas on flexible integrated circuits

“…Unfortunately, the majority of flexible substrates, which are thermoplastics like PEN or PET, have low glass transition and melting temperatures and consequently they can't be exposed to temperatures in the order of 200-300°C in a furnace. Thus, alternative methods of sintering had to be employed in order to fabricate conductive patterns, such as chemical [17] and photonic sintering [18][19][20][21][22][23][24][25][26][27][28][29][30].…”