Organic electrochemical transistors (OECTs) and OECT-based circuitry offer great potential in bioelectronics, wearable electronics and artificial neuromorphic electronics because of their exceptionally low driving voltages (<1 V), low power consumption (<1 µW), high transconductances (>10 mS) and biocompatibility 1 – 5 . However, the successful realization of critical complementary logic OECTs is currently limited by temporal and/or operational instability, slow redox processes and/or switching, incompatibility with high-density monolithic integration and inferior n-type OECT performance 6 – 8 . Here we demonstrate p- and n-type vertical OECTs with balanced and ultra-high performance by blending redox-active semiconducting polymers with a redox-inactive photocurable and/or photopatternable polymer to form an ion-permeable semiconducting channel, implemented in a simple, scalable vertical architecture that has a dense, impermeable top contact. Footprint current densities exceeding 1 kA cm −2 at less than ±0.7 V, transconductances of 0.2–0.4 S, short transient times of less than 1 ms and ultra-stable switching (>50,000 cycles) are achieved in, to our knowledge, the first vertically stacked complementary vertical OECT logic circuits. This architecture opens many possibilities for fundamental studies of organic semiconductor redox chemistry and physics in nanoscopically confined spaces, without macroscopic electrolyte contact, as well as wearable and implantable device applications.

SID Symposium Digest of Technical PapersVolume 52, Issue S1 p. 143-143 Technical Sessions: Session 22: Flexible TFT (joint session with e-Paper and Flexible Displays)Free to Read 22.1: Invited Paper: Active and Passive Organic Materials for Mechanically Flexible and Stable Transistors for Backplane Applications Yu Xia, Yu Xia Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorShiuan-Iou Lin, Shiuan-Iou Lin Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorYang-Cheng Shih, Yang-Cheng Shih Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorShaofeng Lu, Shaofeng Lu Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorAntonio Facchetti, Antonio Facchetti Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this author Yu Xia, Yu Xia Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorShiuan-Iou Lin, Shiuan-Iou Lin Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorYang-Cheng Shih, Yang-Cheng Shih Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorShaofeng Lu, Shaofeng Lu Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorAntonio Facchetti, Antonio Facchetti Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this author First published: 24 February 2021 https://doi.org/10.1002/sdtp.14408AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume52, IssueS1International Conference on Display Technology (ICDT 2020)February 2021Pages 143-143 RelatedInformation

Evaluating the biomechanics of soft tissues at depths well below their surface, and at high precision and in real time, would open up diagnostic opportunities. Here, we report the development and application of miniaturized electromagnetic devices, each integrating a vibratory actuator and a soft strain-sensing sheet, for dynamically measuring the Young’s modulus of skin and of other soft tissues at depths of approximately 1–8 mm, depending on the particular design of the sensor. We experimentally and computationally established the operational principles of the devices and evaluated their performance with a range of synthetic and biological materials and with human skin in healthy volunteers. Arrays of devices can be used to spatially map elastic moduli and to profile the modulus depth-wise. As an example of practical medical utility, we show that the devices can be used to accurately locate lesions associated with psoriasis. Compact electronic devices for the rapid and precise mechanical characterization of living tissues could be used to monitor and diagnose a range of health disorders.

SID Symposium Digest of Technical PapersVolume 52, Issue S2 p. 608-608 Technical Sessions: Session 50: Organic TFT (Joint Session of AMD with E-paper and Flexible Displays) 50.2: Invited Paper: Organic Materials for High-Performance and Flexible TFT Backplanes Antonio Facchetti, Antonio Facchetti Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorYu Xia, Yu Xia Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorShaofeng Lu, Shaofeng Lu Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorShiuan-Iou Lin, Shiuan-Iou Lin Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorKuang-Yao Cheng, Kuang-Yao Cheng Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorLiang-Je Lai, Liang-Je Lai Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorYang-Cheng Shih, Yang-Cheng Shih Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this author Antonio Facchetti, Antonio Facchetti Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorYu Xia, Yu Xia Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorShaofeng Lu, Shaofeng Lu Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorShiuan-Iou Lin, Shiuan-Iou Lin Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorKuang-Yao Cheng, Kuang-Yao Cheng Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorLiang-Je Lai, Liang-Je Lai Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this authorYang-Cheng Shih, Yang-Cheng Shih Flexterra Corporation, Skokie, Illinois, USASearch for more papers by this author First published: 26 August 2021 https://doi.org/10.1002/sdtp.15219AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume52, IssueS2International Conference on Display Technology (ICDT 2021)August 2021Pages 608-608 RelatedInformation

Chemical doping is a key process for investigating charge transport in organic semiconductors and improving certain (opto)electronic devices1–9. N(electron)-doping is fundamentally more challenging than p(hole)-doping and typically achieves a very low doping efficiency (η) of less than 10%1,10. An efficient molecular n-dopant should simultaneously exhibit a high reducing power and air stability for broad applicability1,5,6,9,11, which is very challenging. Here we show a general concept of catalysed n-doping of organic semiconductors using air-stable precursor-type molecular dopants. Incorporation of a transition metal (for example, Pt, Au, Pd) as vapour-deposited nanoparticles or solution-processable organometallic complexes (for example, Pd2(dba)3) catalyses the reaction, as assessed by experimental and theoretical evidence, enabling greatly increased η in a much shorter doping time and high electrical conductivities (above 100 S cm−1; ref. 12). This methodology has technological implications for realizing improved semiconductor devices and offers a broad exploration space of ternary systems comprising catalysts, molecular dopants and semiconductors, thus opening new opportunities in n-doping research and applications12, 13. Electron doping of organic semiconductors is typically inefficient, but here a precursor molecular dopant is used to deliver higher n-doping efficiency in a much shorter doping time.

Compact electronic systems that perform rapid, precise mechanical characterization of living biological tissues have important potential uses in monitoring and diagnosing various types of human-health disorders. Active devices that perform high-precision, real-time evaluations of deep tissue structures (millimeter-scale) in a precise, digital and non-invasive fashion could complement capabilities of recently-reported approaches for sensing tissue biomechanics at superficial depths (typically micrometer-scale). This paper introduces a miniature electromagnetic platform that combines a vibratory actuator with a soft strain-sensing sheet for determining the Young’s modulus of soft biological tissues, with specific focus on skin. Experimental and computational studies establish the operational principles and performance attributes through evaluations of synthetic and biological materials, including human skin at various body locations across healthy subject volunteers. The results demonstrate dynamic monitoring of elastic modulus at characteristic depths between ~1 and ~8 mm, depending on the sensor designs. Arrays of such devices support capabilities in both depth profiling and spatial mapping. Clinical studies on patients with skin disorders highlight potential for accurate targeting of lesions associated with psoriasis, as examples of practical medical utility.

Flexible biocompatible electronic systems that leverage key materials and manufacturing techniques associated with the consumer electronics industry have potential for broad applications in biomedicine and biological research. This study reports scalable approaches to technologies of this type, where thin microscale device components integrate onto flexible polymer substrates in interconnected arrays to provide multimodal, high performance operational capabilities as intimately coupled biointerfaces. Specificially, the material options and engineering schemes summarized here serve as foundations for diverse, heterogeneously integrated systems. Scaled examples incorporate >32,000 silicon microdie and inorganic microscale light-emitting diodes derived from wafer sources distributed at variable pitch spacings and fill factors across large areas on polymer films, at full organ-scale dimensions such as human brain, over ∼150 cm2 In vitro studies and accelerated testing in simulated biofluids, together with theoretical simulations of underlying processes, yield quantitative insights into the key materials aspects. The results suggest an ability of these systems to operate in a biologically safe, stable fashion with projected lifetimes of several decades without leakage currents or reductions in performance. The versatility of these combined concepts suggests applicability to many classes of biointegrated semiconductor devices.

Metal oxide (MO) semiconductor thin films prepared from solution typically require multiple hours of thermal annealing to achieve optimal lattice densification, efficient charge transport, and stable device operation, presenting a major barrier to roll-to-roll manufacturing. Here, we report a highly efficient, cofuel-assisted scalable combustion blade-coating (CBC) process for MO film growth, which involves introducing both a fluorinated fuel and a preannealing step to remove deleterious organic contaminants and promote complete combustion. Ultrafast reaction and metal-oxygen-metal (M-O-M) lattice condensation then occur within 10-60 s at 200-350 °C for representative MO semiconductor [indium oxide (In2O3), indium-zinc oxide (IZO), indium-gallium-zinc oxide (IGZO)] and dielectric [aluminum oxide (Al2O3)] films. Thus, wafer-scale CBC fabrication of IGZO-Al2O3 thin-film transistors (TFTs) (60-s annealing) with field-effect mobilities as high as ∼25 cm2 V-1 s-1 and negligible threshold voltage deterioration in a demanding 4,000-s bias stress test are realized. Combined with polymer dielectrics, the CBC-derived IGZO TFTs on polyimide substrates exhibit high flexibility when bent to a 3-mm radius, with performance bending stability over 1,000 cycles.

Noncovalent conformational locks are broadly employed to construct highly planar π‐conjugated semiconductors exhibiting substantial charge transport characteristics. However, current chalcogen‐based conformational lock strategies for organic semiconductors are limited to S···X (X = O, N, halide) weak interactions. An easily accessible (minimal synthetic steps) and structurally planar selenophene‐based building block, 1,2‐diethoxy‐1,2‐bisselenylvinylene ( DESVS ), with novel Se···O noncovalent conformational locks is designed and synthesized. DESVS unique properties are supported by density functional theory computed electronic structures, single crystal structures, and experimental lattice cohesion metrics. Based on this building block, a new class of stable, structurally planar, and solution‐processable conjugated polymers are synthesized and implemented in organic thin‐film transistors (TFT) and organic photovoltaic (OPV) cells. DESVS ‐based polymers exhibit carrier mobilities in air as high as 1.49 cm 2 V −1 s −1 (p‐type) and 0.65 cm 2 V −1 s −1 (n‐type) in TFTs, and power conversion efficiency >5% in OPV cells.

Benzo[d][2,1,3]thiadiazole (BT) is a markedly electron-deficient heterocycle widely employed in the realization of organic semiconductors for applications spanning transistors, solar cells, photodetectors, and thermoelectrics. In this contribution, we implement the corresponding isomer, benzo[d][1,2,3]thiadiazole (isoBT), along with new 6-fluoro-isoBT and 5,6-difluoro-isoBT units as synthons for constructing alternating copolymers with tetrathiophene (P1–P3). New isoBT-based small molecules as well as the corresponding BT-quaterthiophene based polymers (P4–P6) are synthesized and characterized to probe architectural, electronic structural, and device performance differences between the two families. The results demonstrate that isoBT complements BT in enabling high-performance optoelectronic semiconductors with P3 exhibiting hole mobilities surpassing 0.7 cm2/(V s) in field-effect transistors and power conversion efficiencies of 9% in bulk-heterojunction solar cells.

The cross-plane thermal conductivity of In-GaZnO (IGZO) thin films was measured using the 3 omega. technique from 18 to 300 K. The studied morphologies include amorphous (a-IGZO), semicrystalline (semi-c-IGZO), and c-axis-aligned single-crystal-like IGZO (c-IGZO) grown by pulsed laser deposition (PLD) as well as a-IGZO deposited by sputtering and by solution combustion processing. The atomic structures of the amorphous and crystalline films were simulated with ab initio molecular dynamics. The film quality and texturing information was assessed by X-ray diffraction and grazing incidence wide-angle X-ray scattering. X-ray reflectivity was also conducted to quantify film densities and porosities. All the high-density films exhibit an empirical power law temperature dependence of the thermal conductivity kappa similar to T-0.6 in the specified temperature range. Among the PLD dense films, semi-c-IGZO exhibits the highest thermal conductivity, remarkably exceeding both films with more order (c-IGZO) and with less order (a-IGZO) by a factor of 4. The less dense combustion-synthesized films, on the other hand, exhibited lower thermal conductivity, quantitatively consistent with a porous film using either an effective medium or percolation model. All samples are consistent with the porosity-adapted Cahill-Pohl (p-CP) model of minimum thermal conductivity.

A new photo‐patternable and thermally‐stable organic gate insulator has been developed specifically for IGZO TFTs. Combined with an optimized device platform, flexible IGZO TFTs show groundbreaking performance such as high field‐effect mobilities, negligible I‐V hysteresis, excellent optical transparency and good thermal and bias‐temperature stress stability. A 5" flexible AMOLED utilizes these technologies has been fabricated.

Metal-oxide (MO) semiconductors have emerged as enabling materials for next generation thin-film electronics owing to their high carrier mobilities, even in the amorphous state, large-area uniformity, low cost, and optical transparency, which are applicable to flat-panel displays, flexible circuitry, and photovoltaic cells. Impressive progress in solution-processed MO electronics has been achieved using methodologies such as sol gel, deep-UV irradiation, preformed nanostructures, and combustion synthesis. Nevertheless, because of incomplete lattice condensation and film densification, high-quality solution-processed MO films having technologically relevant thicknesses achievable in a single step have yet to be shown. Here, we report a low-temperature, thickness-controlled coating process to create high-performance, solution-processed MO electronics: spray-combustion synthesis (SCS). We also report for the first time, to our knowledge, indium-gallium-zinc-oxide (IGZO) transistors having densification, nanoporosity, electron mobility, trap densities, bias stability, and film transport approaching those of sputtered films and compatible with conventional fabrication (FAB) operations.

Semiconducting bispyrrolothiophenes for thin film organic field effect transistors were constructed from vinyl azides using transition-metal-catalyzed CH bond functionalization. Pictured is an AFM image of one of the polycrystalline bispyrrolothiophenes that exhibited good field effect transistor performance despite its amorphous nature. For more information see the Full Paper by A. Facchetti, T. G. Driver et al. on page 5938 ff.

AbstractNovel approaches including combustion synthesis achieved via both spin‐coating/post annealing and spray‐coating/in‐situ annealing can be used to generate high‐quality metal oxide thin films, including IGZO, and high performance metal oxide TFTs at relatively low temperatures. Furthermore, we demonstrate metal oxide TFTs using proprietary solution‐processed dielectric and passivation layers.

A series of new highly soluble bispyrrolothiophenes were synthesized from vinyl azides by using transition-metal-catalyzed C-H-bond functionalization. In addition to modifying the substituents present on the end-pyrrolothiophene moieties, the arene linker in between the two units was also varied. The solution-state properties and field-effect-transistor (FET) electrical behavior of these bispyrrolothiophenes was compared. Our investigations identified that the optical properties and oxidation potential of our compounds were dominated by the pyrrolothiophene unit with a λmax  value of approximately 400 nm and oxidation at approximately 1 V. FET devices constructed with thin films of these bispyrrolothiophenes were also fabricated by means of thin-film solution processing. One of these compounds, a bispyrrolothiophene linked with benzothiodiazole, exhibits a mobility of approximately 0.3 cm(2)  V(-1)  s(-1) and the Ion/Ioff value is greater than 10(6).