Electricity and Control September 2021

ENGINEERING THE FUTURE

Printed/flexible electronics in evolving automotive technologies

A lthough vehicle interiors may be an obvious target for emerging technologies based on printed, flexible elec- tronics, there are also plenty of opportunities on vehicle ex- teriors. These range from transparent heaters to solar pan- els, and incorporate attributes as varied as transparency, conformality, low weight, and tunable absorption spectra. Transparent heaters In autonomous vehicles or advanced driver assistance systems (ADAS), cameras and lidar will always require a clear view of the road. This means ensuring that a transparent cover over the sensor is free of mist or frost is essential. While simple, this requirement is significantly more challenging in an electric vehicle as there is far less residual heat generated than with a conventional combustion engine. A similar point applies to LED headlights – because they are much more efficient than halogen bulbs insufficient waste heat is generated to melt ice on the headlight covers. Transparent heaters can provide a solution. These can be created by embedding printed metal wiring via in-mould electronics (IME), or by using transparent conductors such as silver nanowires, carbon nanotubes (CNTs), or met- al mesh. Over time these technologies are likely to fall in price, so they could be applied to windows as well, over- coming the need to scrape ice off car windows. Connected cars need integrated antennas Vehicles becomemore connected every year, necessitating multiple antennas to cover multiple frequency bands. One approach is to integrate these antennas into plastic body panels, which could be achieved either by using in-mould electronics or by printing directly onto 3D surfaces. Windows, as another non-metallic area of vehicles, could also be used for antennas. This approach would clearly require transparent conductors. Possible transparent con- ductor materials, all of which can be printed, include silver nanowires, carbon nanotubes, fine metal mesh, and even very thin layers of particle-free ink. Hybrid SWIR for ADAS ADAS and autonomous vehicles will require a continuous stream of information about their surroundings. This data is likely to originate from multiple sources such as lidar, radar, and cameras to increase redundan- cies, an approach known as sensor fusion. This demand for a range of sensors creates an op- portunity for hybrid short-wave infra-red (SWIR) sen- sors, which require a layer of printed semiconducting material on top of a CMOS (complementary metal-ox- ide semiconductor) readout circuit. The printed layer can be either an organic semiconductor or quantum dots, with the aim in both cases being to extend the spectral sensitivity beyond that of silicon into the SWIR region.

Photovoltaics to increase battery life While photovoltaics could not power a car contin- uously over a long journey, they do enable around 30 km of distance to be added each day. For cars that are used only for short trips around cities, this would remove the need to recharge, greatly increasing convenience. Furthermore, integrated photovoltaic panels can provide power for ancil- lary functions, such as air conditioning, when the vehicle is parked, without drawing on the batteries. At present, the few electric vehicles with inte- grated solar panels use silicon photovoltaics, the established technology with proven durability. However, emerging thin film photovoltaics such as those based on organic and even perovskite sem- iconductors are promising alternatives due to their low weight and conformality. The latter is important if solar panels were to be used one day to coat the entire exterior surface of the car. Exterior displays for autonomous vehicles As vehicles become increasingly autonomous, they will need to interact with pedestrians. One solution to this po- tential challenge is to incorporate a large display on the bonnet of the car that can relay information such as wheth- er or not it is safe for a pedestrian to step in front of the vehicle at a crossing. Low-cost printed/flexible displays are suited to this purpose, as low weight, durability, and confor- mality (including in an accident) are all more important than resolution. Possible approaches include printed LEDs, and mounting LEDs on flexible substrates. Extensive opportunities In summary, there are extensive opportunities for printed and flexible electronics in evolving automotive technolo- gies. In a new report titled Printed and Flexible Electronics for Automotive Applications 2021-2031: Technologies and Markets , IDTechEx outlines the current status and opportu- nities across 11 application areas and looks at companies operating in this space and market forecasts.

Dr Matt Dyson, Senior Technology Analyst at IDTechEx and author of the report, Printed and Flexible Electronics for Automotive Applications 2021- 2031.

For more information visit: www.IDTechEx.com.

Developments in the automotive sector create new opportunities for printed, flexible electronics.

Electricity + Control SEPTEMBER 2021

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