Laser printing of Metal nano-inks
Laser Induced Forward Transfer of Ag Nanoparticle inks for ITO-free organic photovoltaics
NTUA has demonstrated the laser printing and sintering of silver nanoparticle inks as bottom electrodes for the fabrication of Indium Tin Oxide (ITO) -free organic photovoltaics [1], in the frame of the H2020 funded project “RoLA-FLEX”. Combining the so called “Laser Induced Forward Transfer” (LIFT) technique with selective laser sintering, conductive grids displaying high optical transmittance (77% compared to 81% for ITO) and reduced resistivity value (27μOhm*cm compared to 30 μOhm*cm for ITO) were fabricated on glass substrates (Figure 1). These grids were employed as bottom electrodes on inverted structure ITO-free OPV solar cells which exhibited high power conversion efficiency (PCE) of 11%.
Figure 1. Laser printed and sintered bottom electrode for organic solar cells. (a) Schematic representation of laser printing and sintering process (b) Optical transmittance measurements for 6-9-12 lines grids (c) Resistivity measurements for a range of laser sintering powers.
RoLA-FLEX has thus demonstrated the capability of the LIFT and laser sintering techniques to manufacture additively conductive grids as replacers of Indium Tin Oxide (ITO) for the next generation of organic photovoltaics.
Ref. [1] Pozov, S. M., Andritsos, K., Theodorakos, I., Georgiou, E., Ioakeimidis, A., Kabla, A., Melamed, S., de la Vega, F., Zergioti, I. and Choulis, S. A. (2022). Indium Tin Oxide-Free Inverted Organic Photovoltaics Using Laser-Induced Forward Transfer Silver Nanoparticle Embedded Metal Grids. ACS Applied Electronic Materials.
Laser Induced Forward Transfer of Ag Nanoparticle inks for flexible organic TFTs
NTUA has demonstrated the conformal laser printing and sintering of silver nanoparticle inks for the digital and additive manufacturing of organic Organic Thin Film Transistors (OTFT) involved in the next generation of organic displays within the H2020 funded project “RoLA-FLEX“. Employing the so-called “Laser Induced Forward Transfer” technique, Ag nanoparticle inks were printed to linear structures with line-width down to 80 μm and line-height of 500 nm on flexible chips consisting of multiple functional layers [1]. These linear microelectrodes were then laser sintered to obtain metallic conductivity and served as top gate electrodes for OTFT structures developed for a next-generation organic liquid crystal display (OLCD). Organic semiconductor performance tests indicated that the laser fabricated devices achieved performances comparable to the standard manufacturing process (photolithography), implemented in a significantly smaller number of processing steps and without the involvement of any masks (Figure 1).
Figure 1 Laser printing and sintering for the fabrication of a flexible OTFT. (a) Schematic representation of laser printing and sintering process (b) Conformal printing and sintering of top gate electrode lines (c) Flexible test elements with organic semiconductor performance comparable with devices manufactured with standard fabrication techniques.
Ref. [1] Andritsos, K., Theodorakos, I., Zacharatos, F., Kabla, A., Melamed, S., de la Vega, F., Porte Y., Too P. & Zergioti, I. (2023). Conformal laser printing and laser sintering of Ag nanoparticle inks: a digital approach for the additive manufacturing of micro-conductive patterns on patterned flexible substrates. Virtual and Physical Prototyping, 18(1), e2138462
This project has received funding from the European Union’s Horizon 2020 research and innovation programme
under grant agreement n°862474, project RoLA-FLEX