GREEN SYNTHESIS OF ORGANIC SEMICONDUCTORS
The synthetic access to known and performing p and n-type polymeric materials was redesigned, dramatically reducing both E-Factor and atom economy. Key features of the approach where: a) removal of toxic/hazardous reagents, b) minimization of VOCs, c) improvement of yields through process intensification; d) use of water as the main solvent.
SUSTAINABLE SUBSTRATES
The inherent roughness of paper and cellulose-based substrates, making them not compatible with thin-film printed electronics, was tackled by developing different planarization layers. Multilayered structures using paper/cellulose matrices compatible with various printing techniques (e.g. screen printing and inkjet printing) were developed. The prepared substrates are flexible, with a surface roughness < 100 nm and thicknesses in the 150 to 200 µm range. Promising candidates for inkjet printing of tag components were identified.
SUSTAINABLE DIELECTRICS
A sustainable and solution-based process to fabricate ultrathin dielectric films was developed starting from cellulose-derived materials. The films can be easily released in water and transferred onto different substrates, enabling the fabrication of flexible and high-capacitance capacitors. The resulting devices showed stable electrical behavior and capacitance values exceeding the project targets.
UHF COMPONENTS
Two specific challenges were tackled: i) engineering of UHF devices based on solution-processed high-mobility organic semiconducting blends and ii) development of inkjet printing formulations and printing protocols of the same blends. The 1st activity led to the development of short-channel OFETs, with micron-sized direct-written metal electrodes, achieving a transition frequency in the VHF range with reduce operation voltage. The 2nd task delivered OFETs based on inkjet printed semiconductor blend with charge mobility of 8 cm2/Vs in long-channel devices, in line with spin-coated samples.
UHF antennas were designed and fabricated using highly conductive graphene sheets on sustainable paper substrates. The performance of the realized antennas operating at 400 MHz and 433 MHz was validated, obtaining S11 values (reflection coefficient) of −8 dB and −12 dB, respectively. A graphene-based antenna operating at 866 MHz was also designed and fabricated on a paper substrate, then validated using a commercially available UHF RFID EM4325 chip and UHF RFID reader, achieving a communication range of up to 6.5 m.
PRINTED LOGIC
The development of complementary printed organic logic circuits was approached by transitioning to an inkjet printing tool more suitable for reliable, high-yield large-area processing. Source and drain gold contacts arrays were printed with high yield from a water based ink, and validated in reference p-type and n-type OFETs.
LCA
Environmental design guidelines based on an eco-design approach were developed, aligned with ESPR, Green Chemistry principles, Safe and Sustainable by Design, and circular electronics frameworks. Relevant indicators were defined, and quantitative metrics such as E-factor and atom economy were included to assess polymer semiconductor synthesis. Environmental benchmarks for materials and devices were developed, selecting reference organic materials and performing LCAs, as well as establishing an RFID tag benchmark with different antenna materials. The eco-design methodology was applied to assess green synthesis protocols and antenna manufacturing, comparing results with benchmarks, identifying hotspots, and sharing findings with project partners to guide more sustainable material and design choices.
ELECTRONIC DESIGN
The design specifications for the organic UHF tag circuit were defined, addressing both the overall system and the individual sub‑components, including the antenna, organic rectifier, code generator, and backscatter modulator. A suitable architecture for the target demonstrator has also been proposed, integrating all these sub‑components using an heterogeneous approach. As the development of the complementary OFETs technology may lead to unforeseen performance limitations, several alternative UHF tag architectures have been proposed as suitable mitigation strategies.
