Next-generation wearable electronics calls for flexible non-volatile devices for ubiquitous data storage. Thus far, only organic ferroelectric materials have shown intrinsic flexibility and processibility on plastic substrates. Here, we discovered that by controlling the heating rate, ferroelectric hafnia films can be grown on plastic substrates. The resulting highly flexible capacitor with a film thickness of 30 nm yielded a remnant polarization of 10 μC/cm 2 . Bending test shows that the film ferroelectricity can be retained under a bending radius below 8 mm with bending cycle up to 1,000 times. The excellent flexibility is due to the extremely thin hafnia film thickness. Using This article is protected by copyright. All rights reserved. the ferroelectric film as a gate insulator, a low voltage non-volatile vertical organic transistor was demonstrated on a plastic substrate with an extrapolated date retention time up to 10 years.

Intrinsically stretchable semiconductors will facilitate the realization of seamlessly integrated stretchable electronics. However, to date demonstrations of intrinsically stretchable semiconductors have been limited. In this study, a new approach to achieve intrinsically stretchable semiconductors is introduced by blending a rigid high-performance donor-acceptor polymer semiconductor poly[4(4,4dihexadecyl4Hcyclopenta [1,2b:5,4b' ] dithiopen2yl) alt [1,2,5] thiadiazolo [3,4c] pyridine] (PCDTPT) with a ductile polymer semiconductor poly(3hexylthiophene) (P3HT). Under large tensile strains of up to 75%, the polymers are shown to orient in the direction of strain, and when the strain is reduced, the polymers reversibly deform. During cyclic strain, the local packing order of the polymers is shown to be remarkably stable. The saturated field effect charge mobility is shown to be consistently above 0.04 cm2 V-1s-1 for up to 100 strain cycles with strain ranging from 10% to 75% when the film is printed onto a rigid test bed. At the 75% strain state, the charge mobility is consistently above 0.15 cm2 V-1s-1. Ultimately, the polymer blend process introduced here results in an excellent combination of device performance and stretchability providing an effective approach to achieve intrinsically stretchable semiconductors.

Stretchable conductive polymer films are required to survive not only large tensile strain but also stay functional after the reduction in applied strain. In the deformation process, the elastomer substrate that is typically employed plays a critical role in response to the polymer film. In this study, we examine the role of a polydimethylsiloxane (PDMS) elastomer substrate on the ability to achieve stretchable PDPP-4T films. In particular, we consider the adhesion and near-surface modulus of the PDMS tuned through UV/ozone (UVO) treatment on the competition between film wrinkling and plastic deformation. We also consider the role of PDMS tension on the stability of films under cyclic strain. We find that increasing the near-surface modulus of the PDMS and maintaining the PDMS in tension throughout the cyclic strain process promote plastic deformation over film wrinkling. In addition, the UVO treatment increases film adhesion to the PDMS resulting in a significantly reduced film folding and delamination. For a 20 min UVO-treated PDMS, we show that a PDPP-4T film root-mean-square roughness is consistently below 3 nm for up to 100 strain cycles with a strain range of 40%. In addition, although the film is plastically deforming, the microstructural order is largely stable as probed by grazing incidence X-ray scattering and UV–visible spectroscopy. These results highlight the importance of neighboring elastomer characteristics on the ability to achieve stretchable polymer semiconductors.

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stretchable conductor is to disperse conductive 0D, 1D, and 2D nanomaterials onto soft elastomeric substrates. These include nanoparticles, [6][7][8] carbon nanotubes, [9][10][11] silver nanowires, [12][13][14] and graphene, [15][16][17][18][19] all of which have demonstrated high conductivity and large stretchability. Another method is based on geometry, where thin conductive layers with micro/nanoscale corrugated structure maintain conductivity by unbending during stretching. These structures can be induced by surface buckling [19][20][21][22] or self-assembled patterns. [23] Our recent work has demonstrated that interference lithography and atomic layer deposition (ALD) can be used to create a freestanding nano-accordion structure, [24,25] which can be simultaneously stretchable, conductive, and transparent. This approach allows precise control of the structure period, height, and thickness to allow independent design of material properties. However, this approach relies on ALD of the conductive film, which has high cost and long deposition time. The ability to obtain conformal thinfilm coating using a low-cost process can facilitate scale-up manufacturing and broad implementation of flexible electronics.ALD is a widely employed vapor phase technique, where two gas precursors are introduced in alternating cycles to create a self-limited surface reaction. [26,27] Each cycle result in a single monolayer coating, allowing precise control of film thickness by using discrete cycles. Since the gas precursors can permeate within rough topography and deep pores, ALD has demonstrated conformal coating in high-aspect-ratio grating structures, [24,25] high-density nanoscale features, [28,29] and 3D porous lattice. [30][31][32][33][34] However, ALD also has a number of drawbacks, such as long reaction time and expensive precursor gases, contributing to high process cost. Compared with physical vapor deposition (PVD), the selection of deposition material is also limited. Furthermore, metal ALD generally requires high synthesis temperature, which can be problematic for polymer surfaces or template structures.A more established alternative is PVD, which is one of the most widely used technique for precise deposition of thin films, including metals and a diverse range of organic/inorganic materials. Representing a class of techniques where the Physical vapor deposition (PVD) is a versatile thin-film coating technique that can deposit a wide selection of inorganic materials at low cost. However, the process is based on line-of-sight transfer, which can lead to shadowing effects and limit film uniformity over nonplanar topographies. This work describes improving conformal PVD coating on polymer nanostructures by increasing surface energy using a thin oxide interlayer deposited by atomic layer deposition (ALD). The proposed ALD-assisted PVD process allows conformal coating at low cost, and can be adopted for a wide variety of materials compatible with tradition PVD. Conformal gold films over nanostructures with 500 nm half-pitch...