Integratable 3D Microtubular Asymmetric Supercapacitors
A three-dimensional (3D) tubular asymmetric micro-supercapacitor (MSC) with small footprint area, high potential window, ultrahigh areal energy density, and long-term cycling stability is fabricated with shapeable materials and modern microelectronic fabrication technologies. Benefiting from the novel architecture, the 3D asymmetric MSC displays an areal capacitance of 88.6 mF cm−2 and areal energy density of 28.69 mW h cm−2, which are superior to most reported interdigitated MSCs. The 3D tubular MSCs has a remarkable cycling stability and a capacitance retention of up to 91.8% over 12 000 cycles. The efficient fabrication methodology can be used to construct various integratable microscale tubular energy storage devices for a new generation of miniaturized electronics.
Magnetic origami for microelectronics
Self-assembly of two-dimensional patterned nanomembranes into three-dimensional microarchitectures has been considered a powerful approach for parallel and scalable manufacturing of the next generation of micro-electronic devices. Here we present an even better approach for the assembly of high-aspect-ratio nanomembranes into microelectronic devices with unprecedented control by remotely programming their assembly behavior under the influence of external magnetic fields. This form of magnetic Origami creates micro energy storage devices with excellent performance and high yield unleashing the full potential of magnetic field assisted assembly for on-chip manufacturing processes.
This work was highlighted in:
- Pressestelle TU-Chemnitz (July 8, 2019)
- Electronik Praxis (July 17, 2019)
- Oiger - neues aus Wirtschaft und Forschung (July 8, 2019)
- Labor Praxis (July 8, 2019)
- Pro Physik (July 8, 2019)
Integrated tubular micro-supercapacitors
The development of durable and multifunctional microsupercapacitors (MSCs) stringently requires a cost-effective and reliable fabrication procedure which is compatible with modern microelectronics industry. In this work, a tubular micro-supercapacitor (TMSC) with greatly reduced footprint area is created by self-assembling two-dimensional (2D) films into “swiss roll” architectures. A polymeric framework consisting of swelling hydrogel and polyimide layers ensures excellent ion transport between poly(3,4-ethylenedioxythiophene) (PEDOT)-based electrodes and provides efficient self-protection of the TMSC against external compression up to about 30 MPa. As-fabricated TMSC arrays can be detached from their surface and transferred onto target substrates. The connection of devices in parallel/series greatly improves their capacity and voltage output.
Microscale organic field-effect transistors
Monolithic integration of microscale organic field-effect transistors (micro-OFETs) is the only and inevitable path towards low-cost large-area electronics and displays. However, to date, such an ultimate technology has not yet evolved due to challenges in positioning and patterning highly crystalline microscale molecular layers as well as in developing micrometer scale integration technologies. In this work, by mastering the local growth of molecular semiconductors on pre-defined terraces and developing nondestructive photolithographic processes, micro-OFET arrays based on single-crystal quasi-two-dimensional molecular layers are created, delivering mobilites up to 34.6 cm2 V-1 s-1. This work demonstrates the feasibility to integrate arrays of short-channel micro-OFETs into electronic circuitry by highly parallel and size scalable fabrication technologies.
Thermal conductivity in radial and planar Si/SiOx hybrid nanomembrane superlattices
Although silicon has been widely used in modern electronic devices, its implementation in thermoelectric applications is still hindered due to its high intrinsic thermal conductivity, which leads to an extremely low energy conversion efficiency. Here, we report substantial reduction in planar thermal conductivities for both radial and planar Si/SiOx hybrid nanomembrane superlattices. By increasing the winding number of radial superlattices the in-plane thermal conductivity decreases continuously. Our results validate the thermal coupling effect among hybrid superlattice structures and shed light on a novel efficient way of managing phonon transport in Si-based devices.
Evidence for self-organized formation of logarithmic spirals during explosive crystallization of amorphous Ge:Mn layers
Logarithmic spirals are found on different length scales in nature, e.g., in nautilus shells, cyclones, and galaxies. We report on the self-organized formation of symmetric logarithmic crystallization spirals in a solid material on the micrometer length scale, namely, in an amorphous Ge:Mn layer on a Ge substrate. After exposure to a single light pulse of a flashlamp array, the Ge:Mn layer is crystallized and reveals a partially rippled surface and logarithmic microspirals. We present a model describing the formation of the crystallization spirals by directional explosive crystallization of the amorphous Ge:Mn layer, which is triggered by the flashlamp light pulse.
Fully integrated organic nanocrystal diode as high performance room temperature NO2 sensor
Full integration of nanoscale molecular structures with reliable electrical contacts has remained a persistent challenge in device fabrication procedures. In this work, by employing rolled-up technology we successfully create organic diodes consisting of molecular nano-pyramid structures sandwiched between metal and strained nanomembrane electrodes. The robust and smooth contacts provided by self-curled metal layers render the molecular nano-pyramids efficient channels for detecting nitrogen dioxide airflow. The devices demonstrate a high average sensitivity (151% ppm−1) and a fast recovery time (12 min) for NO2 detection.
Large-area rolled-up nanomembrane capacitor arrays
Miniaturization of electronic devices and reduction of their footprint areas are essential ingredients towards efficient development of energy autonomous systems and electronic circuitry. We demonstrate the feasibility of fabricating ultracompact energy storage elements employing rolled-up nanotechnology. These elements highlight the flexibility and high yield of the parallel fabrication process, which results in a substantial reduction in the device dimensions and better integration of the devices into future miniaturized electronic systems.
Thermal conductivity of mechanically joined semiconducting/metal nanomembrane superlattices
We fabricate in an unconventional but straight forward way hybrid superlattices consisting of a large number of nanomembranes mechanically stacked on top of each other. The superlattices can consist of an arbitrary composition of n- or p-type doped single-crystalline semiconductors and a polycrystalline metal layer. These hybrid multi-layered systems are fabricated by taking advantage of the self-rolling and pressed-back technique. The time-domain thermoreflectance measurements show a substantial reduction of the cross-sectional heat transport through the nanomembrane superlattice compared to a single nanomembrane layer below 2 W m-1K-1, which represents a reduction of two orders of magnitude compared to the respective bulk values. Scanning thermal atomic force microscopy measurements support the observation of reduced thermal transport on top of the superlattices with a spatial resolution of ~100nm. The low thermal conductivity reveals the potential of this approach to fabricate miniaturized on-chip solutions for energy harvesters in e.g. micro-autonomous systems.
Rolled-up nanomembranes as compact 3D architectures for field effect transistors and fluidic sensing applications
We fabricate inorganic thin film transistors with bending radii of less than 5μm maintaining their high electronic performance with on-off ratios of more than 100000 and subthreshold swings of 160mV/dec. The fabrication technology relies on the roll-up of highly strained semiconducting nanomembranes, which compacts planar transistors into three-dimensional tubular architectures opening intriguing potential for microfluidic applications. Our technique probes the ultimate limit for the bending radius of high performance thin film transistors.
Animation of 3D rolled-up field effect transistor
Self-wound ultra-compact energy storage elements
We have demonstrated the self-assembly of ultra-compact energy storage devices based on self-wound three-dimensional hybrid organic/inorganic nanomembranes. Such ultra-compact elements exhibit capacitances per footprint area higher than their state-of-the-art planar counterparts and reach specific energies comparable to supercapacitors. The combination of self-assembled organic monolayers with inorganic capacitor materials leads to elements with small footprints, remarkable performance and properties strongly correlated with the organic materials incorporated. Our results represent a breakthrough for local on-chip energy storage and energy supply for autonomous systems at the micro- and nanoscale.
This work was highlighted in:
- New Scientist Magazine (June 26, 2010)
- smartgrid (June 27, 2010)
- Pro-Physik.de (August 4, 2010)
- nanowerk (August 4, 2010)
- Scinexx (August 5, 2010)
- materialgates (August 6, 2010)
- electroniknet.de (August 12, 2010)
- GreenTech Germany (August 17, 2010)
- scienceknowledge.org (September 2, 2010)