Elastomeric Nanodielectrics for Soft and Hysteresis‐Free Electronics

Abstract

Elastomeric dielectrics are crucial for reliably governing the carrier densities in semiconducting channels during deformation in soft/stretchable field‐effect transistors (FETs). Uncontrolled stacking of polymeric chains renders elastomeric dielectrics poorly insulated at nanoscale thicknesses, thereby thick films are usually required, leading to high voltage or power consumption for on/off operations of FETs. Here, layer‐by‐layer assembly is exploited to build 15‐nm‐thick elastomeric nanodielectrics through alternative adsorption of oppositely charged polyurethanes (PUs) for soft and hysteresis‐free FETs. After mild thermal annealing to heal pinholes, such PU multilayers offer high areal capacitances of 237 nF cm−2 and low leakage current densities of 3.2 × 10−8 A cm−2 at 2 V. Owing to the intrinsic ductility of the elastomeric PUs, the nanofilms possess excellent dielectric properties at a strain of 5% or a bending radius of 1.5 mm, while the wrinkled counterparts show mechanical stability with negligible changes of leakage currents after repeated stretching to a strain of 50%. Besides, these nanodielectrics are immune to high humidity and conserve their properties when immersed into water, despite their assembly occurs aqueously. Furthermore, the PU dielectrics are implemented in carbon nanotube FETs, demonstrating low‐voltage operations (< 1.5 V) and negligible hysteresis without any encapsulations.

Aramid Nanodielectrics for Ultraconformal Transparent Electronic Skins

“…A slight decline of capacitance is found with increased frequency, which is due to the reduced dipole response of polar functional groups. [11] Considering the presence of a native SiO x layer below the ANDs, the measured capacitance is attributed to series capacitors consisting of SiO As a potential candidate as a conformal substrate for skin-like electronics, ANDs should be easily exfoliated from the process-ing substrates after the device fabrication on ANDs is completed. Surprisingly, unlike other ultrathin dielectrics, such as PI or Parylene, ANDs can be self-delaminated from the handling substrate without sacrificial layers or etching using a mild peeling force.…”

Stretchable and Lithography-Compatible Interconnects Enabled by Self-Assembled Nanofilms with Interlocking Interfaces

“…The metal layer comprises alternative assembly of positively charged polyelectrolyte PDDA, and citric acid stabilized AgNPs (Figure S1), while the PU nanodielectrics consist of subsequent deposition of oppositely charged PU + and PU − , as revealed by their zeta potentials of 43.9 and −47.3 mV in water, respectively (Figure S2). 34 It is conceptualized that in the absence of PU nanodielectrics, the AgNPs merely rest on the substrate surface and scarcely adhere during deformation (Figure 1b). In comparison, the AgNPs can penetrate and mechanically lock with the underlying PU nanodielectrics, if present, during assembly (Figure 1c).…”

“…Out of a myriad of solution-based deposition approaches, layer-by-layer (LbL) assembly stands out as an effective technique for affording uniform and thickness-regulated coatings based on the alternative assembly of two building blocks with complementary interactions. , LbL-assembled conductive films have been demonstrated with metallic nanoparticles or nanowires, carbon nanotubes, graphene, MXene, or other 2D nanomaterials. − Their applications for stretchable conductors have been recently achieved by taking advantage of the mobility of gold nanoparticles , or automatically formed wrinkled structures owing to the deswelling of substrates. , However, the extensibility of their nanofilms with thicknesses downscaled to sub-100 nm, where interfacial interactions play more important roles than intrinsic mechanical properties, ,− has not been seriously studied. In addition, their high-resolution patternability has not been demonstrated.…”

Smart Textile Optoelectronics for Human‐Interfaced Logic Systems

“…Dielectric is a requisite material for fabricating transistors, which plays an important role in governing the carrier densities in semiconducting channels. Conventional dielectrics include polymeric dielectrics (e.g., polyvinylidene fluoride [PVDF], PU, and SEBS) [132,133] and inorganic dielectrics (e.g., SiO 2 , BN, and Sb 2 O 3 ). [134,135] The dangling bonds within the conventional SiO 2 dielectrics will generate a high density of charge carrier scattering centers and trap states at the semiconductor/oxide interface, hindering the mobility of the channel.…”