Room-Temperature Fabrication of High-Performance Amorphous In-Ga-Zn-O/Al2O3 Thin-Film Transistors on Ultrasmooth and Clear Nanopaper

Plant-Based Structures as an Opportunity to Engineer Optical Functions in Next-Generation Light Management

This review addresses the reconstruction of structural plant components (cellulose, lignin, and hemicelluloses) into materials displaying advanced optical properties. The strategies to isolate the main building blocks are discussed, and the effects of fibrillation, fibril alignment, densification, self-assembly, surface-patterning, and compositing are presented considering their role in engineering optical performance. Then, key elements that enable lignocellulosic to be translated into materials that present optical functionality, such as transparency, haze, reflectance, UV-blocking, luminescence, and structural colors, are described. Mapping the optical landscape that is accessible from lignocellulosics is shown as an essential step toward their utilization in smart devices. Advanced materials built from sustainable resources, including those obtained from industrial or agricultural side streams, demonstrate enormous promise in optoelectronics due to their potentially lower cost, while meeting or even exceeding current demands in performance. The requirements are summarized for the production and application of plant-based optically functional materials in different smart material applications and the review is concluded with a perspective about this active field of knowledge.

Memristively programmable transistors

When designing the gate-dielectric of a floating-gate-transistor, one must make a tradeoff between the necessity of providing an ultra-small leakage current behavior for long state retention, and a moderate to high tunneling-rate for fast programming speed. Here we report on a memristively programmable transistor that overcomes this tradeoff. The operation principle is comparable to floating-gate-transistors, but the advantage of the analyzed concept is that ions instead of electrons are used for programming. Since the mass of ions is significantly larger than the effective mass of electrons, gate-dielectrics with higher leakage current levels can be used. We demonstrate the practical feasibility of the device using a proof-of-concept study based on a micrometer-sized thin-film transistor and LT-Spice simulations of 32 nm transistors. Memristively programmable transistors have the potential of high programming endurance and retention times, fast programming speeds, and high scalability.

Performance Enhancement and Bending Restoration for Flexible Amorphous Indium Gallium Zinc Oxide Thin-Film Transistors by Low-Temperature Supercritical Dehydration Treatment

For high-performance and high-lifetime flexible and wearable electronic applications, a low-temperature posttreatment method is highly expected to enhance the device performance and repair the defects induced by the low-temperature fabrication process intrinsically. Particularly, if the method can repair the traces induced by the multiple cycles of bending or deforming, it would overcome current fatal obstacles and provide a vital solution to the rapid development of flexible electronics. In this work, we propose a method to apply low-temperature supercritical CO₂ fluid with a dehydration function to improve or even restore the performance of flexible amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs). After the treatment, the a-IGZO TFT exhibits 3 times improvement drivability up to 0.24 μA/μm, a smaller subthreshold swing of 0.18 V dec^-1, a smaller V_th of 0.25 V, and a larger I_on/I_off ratio of 3.8 × 10⁷. Additionally, the posttreated a-IGZO TFTs possess relatively good uniformity and reproducibility with an on-current standard deviation of 0.047 μA/μm, and the performance of the a-IGZO TFT after the treatment remains almost unchanged even after bending 2500 times at a bending radius of 5 mm. These characteristics are attributed to the improved quality of the channel and gate dielectric. It is worth noting that when this is applied to a flexible TFT-driven organic light-emitting diode lighting system, this treatment method can restore the performance of not only the TFT but also the lighting system, even after the system has been bent more than 600 times and has failed. To date, this is the first time that the bending-track erasing function of the supercritical fluid for flexible systems has been reported, which has the potential to prolong the lifetime of flexible electronics.

Light response behaviors of amorphous In–Ga–Zn–O thin-film transistors via in situ interfacial hydrogen doping modulation

Thin-film transistors (TFTs) based on amorphous In–Ga–Zn–O (a-IGZO) channels present high mobility, large-area uniformity, mechanical flexibility and photosensitivity, and thus have extensive applicability in photodetectors, wearable devices, etc. However, pure a-IGZO based photosensors only exhibit a UV light response with limited sensitivity performance. By utilizing in situ interfacial hydrogen doping, it is demonstrated that the a-IGZO TFTs with the Al₂O₃ dielectric deposited by plasma-enhanced atomic layer deposition at room temperature (RT) have excellent photosensing performance, such as a photoresponsivity of over 6 × 10⁵ A W⁻¹ and a light to dark current ratio up to 10⁷. This is attributed to spontaneous interfacial hydrogen doping into the a-IGZO channel during sputtering deposition of a-IGZO on hydrogen-rich Al₂O₃ films, thus generating subgap states in the band gap of IGZO. Further, color pattern imaging was achieved by employing an array of the color distinguishable devices, and flexibility was demonstrated by fabricating the TFTs onto polymer substrates. Moreover, it is also found that both the RT and 150 °C Al₂O₃ a-IGZO TFTs exhibit typical light-stimulated synaptic behaviors, including excitatory post-synaptic current and pair-pules facilitation, etc., and the memory time of the synaptic devices can be easily modulated by the degree of the interfacial hydrogen doping.

Thin-film transistors (TFTs) based on amorphous In–Ga–Zn–O (a-IGZO) channels present high mobility, large-area uniformity, mechanical flexibility and photosensitivity, and thus have extensive applicability in photodetectors, wearable devices, etc.

Optimizing the Properties of InGaZnOx Thin Film Transistors by Adjusting the Adsorbed Degree of Cs+ Ions

To improve the performance of amorphous InGaZnO_x (a-IGZO) thin film transistors (TFTs), in this thesis, Cs⁺ ions adsorbed IGZO (Cs-IGZO) films were prepared through a solution immersion method at low temperature. Under the modification of surface structure and oxygen vacancies concentrations of a-IGZO film, with the effective introduction of Cs⁺ ions into the surface of a-IGZO films, the transfer properties and stability of a-IGZO TFTs are greatly improved. Different parameters of Cs⁺ ion concentrations were investigated in our work. When the Cs⁺ ions concentration reached 2% mol/L, the optimized performance Cs-IGZO TFT was obtained, showing the carrier mobility of 18.7 cm² V^-1 s^-1, the OFF current of 0.8 × 10^-10 A, and the threshold voltage of 0.2 V, accompanied by the threshold voltage shifts of 1.3 V under positive bias stress for 5000 s.

High-Performance a-InGaZnO Thin-Film Transistors with Extremely Low Thermal Budget by Using a Hydrogen-Rich Al2O3 Dielectric

Electrical characteristics of amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) are compared by using O2 plasma-enhanced atomic layer deposition Al2O3 dielectrics at different temperatures. High-performance a-IGZO TFTs are demonstrated successfully with an Al2O3 dielectric deposited at room temperature, which exhibit a high field-effect mobility of 19.5 cm2 V- 1 s- 1, a small subthreshold swing of 160 mV/dec, a low threshold voltage of 0.1 V, a large on/off current ratio of 4.5 × 108, and superior negative and positive gate bias stabilities. This is attributed to the hydrogen-rich Al2O3 dielectric deposited at room temperature in comparison with higher deposition temperatures, thus efficiently passivating the interfacial states of a-IGZO/Al2O3 and the oxygen vacancies and improving conductivity of the a-IGZO channel by generating additional electrons because of enhanced hydrogen doping during sputtering of IGZO. Such an extremely low thermal budget for high-performance a-IGZO TFTs is very attractive for flexible electronic application.

Paper in Electronic and Optoelectronic Devices

Paper, one of the oldest materials for storage and exchange of human's information, has been reinvented as a building component of electronic and optoelectronic devices over the past decades with successful demonstration of paper-based or paper-using devices. These recent achievements can meet the demand for lightweight, cost-effective, and/or flexible electronic and optoelectronic devices with advanced functionality and reduced manufacturing costs. This article provides a review of electronic and optoelectronic devices relying on or making use of the unique properties achievable with paper-based materials. Basic scientific/technical principles, quantitative comparisons of material, electronic and/or optical properties, and benefits for each paper-based application are given. Application-specific research challenges, future design considerations, and development directions are also discussed.