Large-area potassium-doped highly conductive graphene films for electromagnetic interference shielding

Abstract

As promising carbonaceous films, graphene films (GF) have exhibited many remarkable mechanical and electrical/thermal properties of great potential for wide functional applications. However, the electrical conductivity of GF still needs to be improved and the limitation lies in the low carrier density of pure graphene. Here, we presented a post-doping method for large-area potassium doped graphene films (GF-K) and promoted the electrical conductivity of GF approaching benchmark metals. The macroscopic-assembled GF-K shows a similar color to graphite intercalation compounds. The potassium doping increased the carrier density of the GF without undermining the electronic quality of the graphene unit. The doping concentration was optimized to prepare stage-2 GF-K (CK) with the highest electrical conductivity (1.49 × 10 S m), holding merits of low density (1.63 g cm), and high flexibility. Doped GF with better specific electrical conductivity than copper showed outstanding electromagnetic interference shielding performance. Shielding effectiveness (SE) increased from 70-85 dB for graphene film (GF) to over 130 dB for GF-K only at 31 μm thickness, which is among the best SEs in previous reports. The combination of high specific conductivity, mechanical flexibility, high EMI SE, light weight, and facile productivity enables GF-K to be promising in many high-end EMI applications such as aerospace and wearable devices.

Superhigh Electromagnetic Interference Shielding of Ultrathin Aligned Pristine Graphene Nanosheets Film

“…Alternatively, with good dispersion and processability, graphene oxide (GO), a derivative of graphene, has been widely demonstrated for EMI shielding (Table S1, Supporting Information). [ 28–30 ] However, GO has to be reduced in use since it is electrically insulating. Unfortunately, the electrical conductivity of GO is limited even after reduction, in particular the reduction of GO in polymer is extremely difficult.…”

Ultrathin flexible graphene films with high thermal conductivity and excellent EMI shielding performance using large-sized graphene oxide flakes

“…Aer compression of the PLG lm, SE total of LG-1 lm is signicantly reduced, mainly attributed the remarkable decrease of SE abs and slight decrease of SE ref . According to eqn (7), the decreasing distance between graphene laminates aer compression results in decrease of shielding performance for the PLG lm. Comparing with the PLG lm, the LG-4 lm possesses better EMI SE, because of higher SE abs , which is proportional to increased thickness of graphene laminates.…”

“…Electromagnetic interference (EMI) shielding protection is the most effective way to prevent EM pollution. [4][5][6][7] According to electromagnetic theory, the main mechanisms to reduce undesirable EM emissions include reection of EM radiation by impedance mismatching and absorption of the EM wave energies by dielectric or magnetic loss. 8 Electrically conductive materials are reective shielding materials, which could reect most of the incident waves, due to their high electrical conductivity.…”

“…For the portion of waves able to enter shielding materials, absorption loss is the dominant consumption of this EM energy, which depends on the interaction between conducting parts of shielding materials and EM waves. 7,9,10 Hence, materials with high electrical conductivity, such as metals, carbon materials and conductive polymers, have been applied as effective EMI shielding materials. However, metal shielding materials have the disadvantages of high densities and easy corrosion, limiting their application in lightweight, wearable electronic equipment.…”

Anticorrosive, Ultralight, and Flexible Carbon‐Wrapped Metallic Nanowire Hybrid Sponges for Highly Efficient Electromagnetic Interference Shielding

“…[7a] It is worthwhile to note that metal‐based materials with exceptional intrinsic conductivity possess superior EMI shielding performance when compared with those of graphene and MXenes. [7a,8] Nevertheless, searching for metal‐based materials with the above desired features still is a huge challenge since they cannot simultaneously integrate these intriguing characteristics, including lightweight, flexibility, corrosion‐resistance, and ease of processing. Therefore, some metal‐based materials (such as silver and copper) with ultrahigh EMI SE values are less useful.…”