Printed graphene and its composite with copper for electromagnetic interference shielding applications

Abstract

Advances in mobile electronics and telecommunication systems along with 5G technologies have been escalating the electromagnetic interference (EMI) problem in recent years. Graphene-based material systems such as pristine graphene, graphene-polymer composites and other graphene-containing candidates have been shown to provide adequate EMI shielding performance. Besides achieving the needed shielding effectiveness, the method of applying the candidate shielding material onto the object in need of protection is of enormous importance due to considerations of ease of application, reduced logistics and infrastructure, rapid prototyping and throughput, versatility to handle both rigid and flexible substrates and cost. Printing readily meets all these criteria and here we demonstrate plasma jet printing of thin films of graphene and its composite with copper to meet the EMI shielding needs. Shielding effectiveness over 30 dB is achieved, which represents blocking over 99.9% of the incoming radiation. Graphene and its composite with copper yield higher green index compared to pure copper shields, implying reduced reflection of incoming electromagnetic waves to help reduce secondary pollution.

High green index electromagnetic interference shields with semiconducting Bi2S3 fillers in a PEDOT:PSS matrix

“…Finally, the shielding effectiveness values achieved here are comparable to or exceed the values reported in the literature for metals and emerging materials, which are from 20 to 70 dB, 2–16 but the focus here is rather on green index, which has not been discussed much previously. As mentioned earlier, metals exhibit a very poor green index of well under 0.1 6 and graphene provides a marginally better GI of 0.14.…”

“…As mentioned earlier, metals exhibit a very poor green index of well under 0.1 6 and graphene provides a marginally better GI of 0.14. 11 The only other work discussing green index involves WS 2 in an rGO matrix 17 that also gives a green index close to unity but with only ∼26 dB shielding effectiveness. Sushmita et al 36 review the addition of several oxides and other semiconducting materials to insulating and conducting polymers but no information on green index was given.…”

“…With electronic components getting increasingly smaller, the weight penalty becomes a serious concern with conventional metal shields. Successful alternatives in the literature have included shields based on graphene, 10–12 carbon nanotubes, 13 MXenes 14–16 and other 2D materials. 2,3,17 All these new materials have been shown to mitigate the shortcomings of metals while providing good shielding effectiveness.…”

“…6 EMI shields based on carbon nanomaterials and MXenes are also reflection dominant since these materials are highly conductive. For example, printed graphene has been shown to yield a GI value of 0.14 11 while printed MXene–polymer composite exhibits GI in the range of 0.2–0.6. 16 Note that SE A may be greater than SE R for shields based on these materials but reflection and absorption losses do not represent actual reflected and absorbed power levels and thus, cannot be used to assess the relative contributions of reflection and absorption; further discussion on this with numerical examples is given under ESI †.…”

“…8,9 However, the SE values of pure ICPs are too low to be of practical value and therefore, their composites with various fillers or additives have been widely considered to boost the SE values. Metallic fillers 4,9,20 are the most common additives along with carbon-based fillers 10–12 and most recently MXene fillers, with the latter two fillers also being highly conductive. 13 The filler loading factor varies widely from a few percentages to even 50–60%, depending on the choice of filler and processing technique.…”