Printed and hybrid integrated electronics produced from recycled and renewable materials can reduce the depletion of limited material resources while obtaining energy savings in small electronic applications and their energy storage. In this work, bio-based poly(lactic acid) (PLA) and recycled polyethylene terephthalate (rPET) were fabricated in film extrusion process and utilized as a substrate in ultra-thin organic photovoltaics (OPV). In the device structure, metals and metal oxides were replaced by printing PEDOT:PSS, carbon and amino acid/heterocycles. Scalable, energy-efficient fabrication of solar cells resulted in efficiencies up to 6.9% under indoor light. Furthermore, virgin-PET was replaced with PLA and rPET in printed and hybrid integrated electronics where surface-mount devices (SMD) were die-bonded onto silver-printed PLA and virgin-PET films to prepare LED foils followed by an overmoulding process using the rPET and PLA. As a result, higher relative adhesion of PLA-PLA interface was obtained in comparison with rPET-PET interface. The obtained results are encouraging from the point of utilization of scalable manufacturing technologies and natural/recycled materials in printed and hybrid integrated electronics. Assessment showed a considerable decrease in carbon footprint, about 10–85%, mainly achieved through replacing of silver, virgin-PET and modifying solar cell structure. In outdoor light, the materials with low carbon footprint can decrease energy payback times (EPBT) from ca. 250 days to under 10 days. In indoor energy harvesting, it is possible to achieve EPBT of less than 1 year. The structures produced and studied herein have a high potential of providing sustainable energy solutions for example in IoT-related technologies.

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In this case study, the possibilities of hybrid integration of printed and flexible electronics in combination with conventional electronic components to create new types of product concepts is demonstrated. The final result is a personal activity meter demonstrator, which is realized by utilizing various flexible electronics manufacturing and integration techniques. Roll-to-roll printing was used to print the electronic backplane as well as co-planar electrochromic (EC) display. A pick-and-place assembled microcontroller unit and accelerometer, together with passive components, provided the brains for the system. Injection molding was then utilized to create a structural electronics system including an EC display. To validate the feasibility and scalability of the processes used, 100 pieces of the personal activity meter were fabricated. Modeling with continuum computational fluid dynamics and numerical heat transfer, using the high-performance finite volume method, showed that high filling pressure and shear-stress are the key factors causing broken devices. The stability of the devices in harsh environmental conditions as well as in bending seem to be slightly improved in the over molded samples. INDEX TERMS Electrochromic displays, injection molding, hybrid integration, printed electronics, structural electronics. TERHO KOLOLUOMA received the Ph.D. degree in chemistry from the University of Oulu in 2003. From 1998 to 1999, he was with the University of Oulu having a responsibility on fabrication and characterization of solgel-based materials. From 1999 to 2003, he was with VTT Electronics for developing new materials for optoelectronic applications. During that period, he started the first experiments in the area of roll-to-roll printed electronics and optoelectronics and started to lead various research project in that field. After finishing his Ph.D. thesis in 2003, he started as a Senior Scientist focusing on development of printed electronics components and technologies, and since 2010, he has a Principal Scientist. From 2013 to 2015, he was with National Research Council Canada, he is currently a Research Team Leader of printed electronics processing team with VTT. His main research topic is printable optics and electronics. Of his special interests are novel materials for printed electronics and materials-process interface.

Large area electronics is becoming an embedded part of structural elements such as automotive and architectural glasses. In this study, the effect of glass lamination based fabrication process on the electrical performance and production throughput yield (TPY) of printed conductive wires and surface mounted (SMD) connectors on polyethylene terephthalate (PET) carrier film were investigated by measuring their electrical conductivity after lamination. Based on the experiments, lamination decreases the production yield of conductive wires and connectors due broken wires or dislocated connectors, especially if they are located close to the corners of laminate. On the other hand, lamination was observed to improve the electrical conductivity of wires. In addition, some potential failure mechanisms are discussed.

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