Printed/flexible electronics is a constantly evolving area with extensive scope for innovation. Here, IDTechEx outlines three of the most exciting technological highlights in the sector. These innovations span from technically advanced materials to novel manufacturing methodologies, covering a diverse set of applications that range from OLED displays to wearable healthcare patches.
An especially exciting technical development is fully flexible thinned silicon integrated circuits (ICs). These support capabilities such as Bluetooth previously associated with packaged ICs to be mounted on flexible/curved substrates, enabling a wide range of novel form factors. The flexible ICs are produced by grinding down a convention silicon die to as thin as 3 um before encapsulating it in polyimide, and can have a bending radius as low as 1 mm.
Flexible mounted components are key components of the emerging manufacturing trend known as 'Flexible Hybrid Electronics' (FHE). FHE seeks to resolve some of the compromises inherent in printed electronics by combining mounted components (such as flexible ICs) with printed conductive traces on a flexible substrate. While wearable electronics and smart packaging are forecast to be the most promising applications, FHE can be applied across many sectors. Further details on flexible ICs and FHE, including multiple case studies, can be found in the IDTechEx report "Flexible Hybrid Electronics 2020-2030: Applications, Challenges, Innovations and Forecasts".
Market forecast (by revenue) for the adoption of FHE for various applications. These forecasts are based on a granular analysis of over 20 sub-categories, the benefits offered by FHE in each category, and price forecasts for application specific components and assembly methods. Source: IDTechEx
Advances in OLED Materials
Turning to OLED materials, the dominant technical trend is the emergence of a new class of materials that promise lower-costs, high efficiency, and a wider color gamut. Known as triplet activated delayed fluorescent (TADF) materials, they represent an entirely new approach to ensuring that all the incoming charges are utilized in producing light. Orange emitters, using materials developed by Japanese film Kyulux, have already been commercialized for small displays, with other colors set to follow in 2021.
Additionally, we were especially impressed this year by a novel approach to the host materials, which generally receive less research effort than their emissive counterparts. Developed by early-stage US firm Molecular Glasses, this innovative host material increases the solubility of dopant molecules, be they fluorescent, phosphorescent or TADF, while retaining charge transport capabilities.
This is achieved by making the host material from a wide range of subtly different chemical structures, known as an isomeric mixture. As such, crystallization of the host material is prevented and emissive dopant molecules are more evenly dispersed, thus avoiding aggregation. This in turn reduces interaction between charges and excitons prior to light emission, improving luminescent efficiency. For an extensive discussion of materials for OLEDs, other organic semiconductor applications and indeed many other material categories please see the recently released IDTechEx report "Materials for Printed/Flexible Electronics 2021-2031: Technologies, Applications, Market Forecasts".
Alternatives to Particle Based Conductive Inks
Another exciting and innovative technology, again material based, is an alternative to stretchable conductive inks. Rather than combining silver flakes with elastomeric binders, early-stage company Liquid Wire use a metal gel based on a gallium/indium alloy that is liquid at room temperature. As such, this stretchable conductor does not fatigue following repeated stretching. Furthermore, as a gel it avoids the difficulties in attaching rigid components with different thermal and mechanical properties to the stretchable, polymeric substrate. The circuits are constructed by embedding the metal gel within stacked sheets of stenciled TPU.
Liquid Wire's metal gel and associated component attachment technology is initially targeted at wearable applications, such as monitoring electrical signals inside the body. Wearable electronics are a rapidly growing area, with applications in healthcare, therapeutics, and fitness. A detailed analysis of how printed/flexible electronics is being applied to the healthcare applications is given in the IDTechEx report "Flexible Electronics in Healthcare 2020-2030".
Impact of COVID-19 on Printed and Flexible Electronics
In 2020 some companies have pivoted to providing solutions to address the COVID-19 pandemic. For example, within wearable electronics, remote patient monitoring, including electronic skin patches has seen strong interest for monitoring a patient's temperature remotely, the benefit being that the patient does not need to come into contact with healthcare professionals to take their temperature which may expose them to the virus. Furthermore, conductive ink has been used in sensor test systems as part of a system to detect infections, including COVID-19.
In other areas materials such as nano copper have been developed for their anti-viral benefits, with equipment providers 3D printing the material onto surfaces such as door handles. In retail environments, printed force sensors have been applied into mats to alert shoppers where they are standing too close to each other.
Overall, 2020 has been an exciting year for printed electronics, with an increased focus on the aspects, such as flexible hybrid electronics, that bring a real value proposition to manufacturers and ultimately consumers. IDTechEx expect printed/flexible/hybrid electronics to be increasingly adopted in commercial applications including smart packaging, wearables, automotive interiors, and consumer goods over the next few years.
IDTechEx offers a wide range of technical market research reports covering most aspects of printed/flexible electronics, building on our long history of analyzing these technologies, markets, and applications (www.IDTechEx.com/Research/PE). All reports include detailed analysis of established and emerging technologies, their potential adoption barriers and suitability for different applications, and an assessment of technological and commercial readiness. IDTechEx reports also include multiple company profiles based on interviews with early-stage and established companies, along with 10-year market forecasts. A full list of IDTechEx's reports can be found at www.IDTechEx.com/research.