A bionic self-driven retinomorphic eye with ionogel photosynaptic retina.

Bioinspired bionic eyes should be self-driving, repairable and conformal to arbitrary geometries. Such eye would enable wide-field detection and efficient visual signal processing without requiring external energy, along with retinal transplantation by replacing dysfunctional photoreceptors with healthy ones for vision restoration. A variety of artificial eyes have been constructed with hemispherical silicon, perovskite and heterostructure photoreceptors, but creating zero-powered retinomorphic system with transplantable conformal features remains elusive. By combining neuromorphic principle with retinal and ionoelastomer engineering, we demonstrate a self-driven hemispherical retinomorphic eye with elastomeric retina made of ionogel heterojunction as photoreceptors. The receptor driven by photothermoelectric effect shows photoperception with broadband light detection (365 to 970 nm), wide field-of-view (180°) and photosynaptic (paired-pulse facilitation index, 153%) behaviors for biosimilar visual learning. The retinal photoreceptors are transplantable and conformal to any complex surface, enabling visual restoration for dynamic optical imaging and motion tracking.

Co-assembled perylene/graphene oxide photosensitive heterobilayer for efficient neuromorphics.

Neuromorphic electronics, which use artificial photosensitive synapses, can emulate biological nervous systems with in-memory sensing and computing abilities. Benefiting from multiple intra/interactions and strong light-matter coupling, two-dimensional heterostructures are promising synaptic materials for photonic synapses. Two primary strategies, including chemical vapor deposition and physical stacking, have been developed for layered heterostructures, but large-scale growth control over wet-chemical synthesis with comprehensive efficiency remains elusive. Here we demonstrate an interfacial coassembly heterobilayer films from perylene and graphene oxide (GO) precursors, which are spontaneously formed at the interface, with uniform bilayer structure of single-crystal perylene and well-stacked GO over centimeters in size. The planar heterostructure device exhibits an ultrahigh specific detectivity of 3.1 × 1013 Jones and ultralow energy consumption of 10-9 W as well as broadband photoperception from 365 to 1550 nm. Moreover, the device shows outstanding photonic synaptic behaviors with a paired-pulse facilitation (PPF) index of 214% in neuroplasticity, the heterosynapse array has the capability of information reinforcement learning and recognition.

Multimode Visualization of Electronic Skin from Bioinspired Colorimetric Sensor.

Bioskins possess a great ability to detect and deliver external mechanical or temperature stimuli into identifiable signals such as color changes. However, the integration of visualization with simultaneous detection of multiple complex external stimuli in a single biosensor device remains a challenge. Here we propose an all-solution-processed bioinspired stretchable electronic skin with interactive color changes and four-mode sensing properties. The fabricated biosensor demonstrates sensitive responses to various stimuli including pressure, strain, voltage, and temperature. Sensing visualization is realized by color changes of the e-skin from brown to green and finally bright yellow as a response to intensified external stimuli, suggesting great application potential in military defense, healthcare monitoring, and smart bionic skin.

Wearable and washable light/thermal emitting textiles.

Electronic textiles (e-textiles) typically comprise fabric substrates with electronic components capable of heating, sensing, lighting and data storage. In this work, we rationally designed and fabricated anisotropic light/thermal emitting e-textiles with great mechanical stability based on a sandwich-structured tri-electrode device. By coating silver nanowire network/thermal insulation bilayer on fabrics, an anisotropic thermal emitter can be realized for smart heat management. By further covering the emissive film and the top electrode on the bilayer, light emitters with desirable patterns and colors are extracted from the top surface via an alternative current derived electroluminescence. Both the light and thermal emitting functions can be operated simultaneously or separately. Particularly, our textiles exhibit reliable heating and lighting performance in water, revealing excellent waterproof feature and washing stability.

Recyclable and Flexible Dual-Mode Electronics with Light and Heat Management.

Realizing multiple functions and sustainable manufacturing within the same electronic device would be highly attractive from a design and fabrication perspective. Here we demonstrate a recyclable dual-mode thin-film device that can perform both light emission and heat management simultaneously. The device is composed of a dissolvable emitting layer sandwiched between two undissolvable conducting films. The vertical multilayered device enables a highly flexible and foldable multicolor electroluminescent emission ranging from yellow or blue to white, and the coplanar monolayered conductor achieves tunable Joule heat temperature setting. By utilizing selective dissolution and artificial reconstruction of each layered component, the parent device shows full recyclability and reconstructability without severe performance degradation after several recycles. The proof-of concept device provides an ideal strategy to construct a multifunctional film system with recyclability and makes a significant contribution to scientific and technological advancement in low-cost sustainable electronics and optoelectronics.

Multifunctional Polymer Memory via Bi-Interfacial Topography for Pressure Perception Recognition.

Emerging memory devices, that can provide programmable information recording with tunable resistive switching under external stimuli, hold great potential for applications in data storage, logic circuits, and artificial synapses. Realization of multifunctional manipulation within individual memory devices is particularly important in the More-than-Moore era, yet remains a challenge. Here, both rewritable and nonerasable memory are demonstrated in a single stimuli-responsive polymer diode, based on a nanohole-nanowrinkle bi-interfacial structure. Such synergic nanostructure is constructed from interfacing a nanowrinkled bottom graphene electrode and top polymer matrix with nanoholes; and it can be easily prepared by spin coating, which is a low-cost and high-yield production method. Furthermore, the resulting device, with ternary and low-power operation under varied external stimuli, can enable both reversible and irreversible biomimetic pressure recognition memories using a device-to-system framework. This work offers both a general guideline to fabricate multifunctional memory devices via interfacial nanostructure engineering and a smart information storage basis for future artificial intelligence.

Interfacial synthesis of a large-area coordination polymer membrane for rewritable nonvolatile memory devices.

The facile synthesis of large-area coordination polymer membranes with controlled nanoscale thicknesses is critical towards their applications in information storage electronics. Here, we have reported a facile and substrate-independent interfacial synthesis method for preparing a large-area two-dimensional (2D) coordination polymer membrane at the air-liquid interface. The prepared high-quality 2D membrane could be transferred onto an indium tin oxide (ITO) substrate to construct a nonvolatile memory device, which showed reversible switching with a high ON/OFF current ratio of 103, good stability and a long retention time. Our discovery of resistive switching with nonvolatile bistability based on the substrate-independent growth of the 2D coordination polymer membrane holds significant promise for the development of solution-processable nonvolatile memory devices with a miniaturized device size.

Hierarchical Hollow-Pore Nanostructure Bilayer Heterojunction Comprising Conjugated Polymers for High-Performance Flash Memory.

We report the design and preparation of hierarchical hollow-pore nanostructure bilayer conjugated polymer films for high-performance resistive memory devices. By taking the merits of chemical and structural stabilities of a two-dimensional conjugated microporous polymer (2D CMP), a poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) film with a hollow surface was spin-coated onto 2D CMP nanofilm directly, constructing a bilayer heterojunction. A two-terminal diode with a configuration of indium tin oxide/2D CMP/hollow MEH-PPV/Al was fabricated by employing the prepared bilayer heterojunction. The device poses flash feature with a high on/off ratio (>105) and a long retention time (>3.0 × 104 s), which is higher than that of most of the reported conjugated polymers memories. Our work offers a general guideline to construct high on/off ratio polymer memories via hierarchical nanostructure engineering in memristive layer.

Electrostatically assembled carbon dots/boron nitride nanosheet hybrid nanostructures for thermal quenching-resistant white phosphors.

Carbon dots (C-dots) are promising and widely applied carbon fluorescent materials for next-generation white light-emitting diodes (WLEDs). However, nonnegligible thermal quenching issues induced by high working temperature of high-power WLEDs severely limit the further development of C-dot phosphors. In this paper, we report an efficient strategy to improve thermal dissipation within C-dot phosphors to solve the thermal quenching problem. C-dots/hexagonal boron nitride nanosheet (BNNS) hybrid nanostructures have been firstly prepared through an electrostatic assembly method. Owing to the effective heat transfer channels established by C-dots/BNNS in a polymer matrix, heat could be dissipated efficiently and the working temperature of WLEDs is reduced by 29 °C, suggesting excellent thermal quenching-resistance properties. Particularly, the hybrids show thermally stable emission without obvious emission loss up to 100 °C. Moreover, the C-dots/BNNS-WLEDs still maintain a high color rendering index of Ra > 89, revealing that the present strategy could promote the exploration of carbon phosphors with thermal quenching resistance for high-quality LED applications.

A Universal Strategy for Stretchable Polymer Nonvolatile Memory via Tailoring Nanostructured Surfaces.

Building stretchable memory is an effective strategy for developing next-generation memory technologies toward stretchable and wearable electronics. Here we demonstrate a universal strategy for the fabrication of high performance stretchable polymer memory via tailoring surface morphology, in which common conjugated polymers and sharp reduced graphene oxide (r-rGO) films are used as active memristive layers and conductive electrodes, respectively. The fabricated devices feature write-once-read-many-times (WORM) memory, with a low switching voltage of 1.1 V, high ON/OFF current ratio of 104, and an ideal long retention time over 12000 s. Sharp surface-induced resistive switching behavior has been proposed to explore the electrical transition. Moreover, the polymer memory show reliable electrical bistable properties with a stretchability up to 30%, demonstrating their great potential candidates as high performance stretchable memory in soft electronics.

Quench-resistant and stable nanocarbon dot/sheet emitters with tunable solid-state fluorescence via aggregation-induced color switching.

Nanocarbon fluorescence materials are promising color converters for multicolor emission via phosphor-coated light emitting devices (LEDs). Herein, a facile time-controlled solvothermal route was developed to prepare solid-state multicolor nanocarbon emitters comprising dot/sheet nanohybrids. The nanocarbons demonstrate an aggregation-induced color switching behavior, leading to tunable light emission from blue to yellow by modulating the solvothermal reaction time. Particularly, these emitters show outstanding film-forming ability directly and a high production yield (∼40%). Moreover, the nanocarbon-coated ultraviolet LEDs exhibit high quality multicolor light emission and excellent color stability at high voltages, impelling the development of emerging carbon phosphors in fundamental research studies and practical applications.

Preparation of large-area ultrathin carbon semiconductors converted from conjugated microporous polymer films.

Two-dimensional carbon semiconductors have aroused great attention due to their unique structures and novel properties, showing potential applications in emerging electronic and optoelectronic devices. In this work, we reported an effective strategy to controllable prepare ultrathin carbon nanofilms (CNFs) by combining in situ-growth and stepwise thermal annealing, with the features of large-area, tunable properties and nanoscale thickness. The structures, morphologies and electrical properties of these as-prepared CNFs were characterized systematically. Impressively, tunable electrical properties from low to semi- and high conductivity could be precisely achieved through stepwise annealing of conjugated microporous polymer films. By introducing CNF-750 as the active channel layer, the transistor exhibited a typical p-type semiconductor property. Moreover, by further coupling CNF-750 with carbon dots (CDs) as a photoresponse layer, the as-fabricated all-carbon diode based on CDs/CNF-750 heterostructure film showed high ultraviolet (UV) light response.

Zero- and two-dimensional hybrid carbon phosphors for high colorimetric purity white light-emission.

Carbon nanomaterials are promising phosphors for white light emission. A facile single-step synthesis method has been developed to prepare zero- and two-dimensional hybrid carbon phosphors for the first time. Zero-dimensional carbon dots (C-dots) emit bright blue luminescence under 365 nm UV light and two-dimensional nanoplates improve the dispersity and film forming ability of C-dots. As a proof-of-concept application, the as-prepared hybrid carbon phosphors emit bright white luminescence in the solid state, and the phosphor-coated blue LEDs exhibit high colorimetric purity white light-emission with a color coordinate of (0.3308, 0.3312), potentially enabling the successful application of white emitting phosphors in the LED field.

Polymer-carbon dot hybrid structure for a self-rectifying memory device by energy level offset and doping.

A strategy for self-rectifying memory diodes based on a polymer-carbon dot hybrid structure, with a configuration of rGO/PEDOT : PSS/carbon dots/MEH-PPV/Al, has been proposed. The fabricated device exhibits a rectification of 103 in the rectification model and an ON/OFF current ratio of 121 in the memory model. The rectifying behavior was attributed to an energy level offset between the electrodes and the bilayer polymers and the memory effect was induced by carrier trapping of carbon dots within the polymers.