Carlos

Solar cells have been considered as one of the foremost solutions to energy and environmental problems because of clean, high efficiency, cost-effective, and inexhaustible features. The historical development and state-of-the-art solar cells mainly focus on elevating photoelectric conversion efficiency upon direct sunlight illumination. It is still a challenging problem to realize persistent high-efficiency power generation in rainy, foggy, haze, and dark-light conditions (night). The physical proof-of-concept for all-weather solar cells opens a door for an upcoming photovoltaic revolution. Our group has been exploring constructive routes to build all-weather solar cells so that these advanced photovoltaic technologies can be an indication for global solar industry in bringing down the cost of energy harvesting. How the all-weather solar cells are built without reducing photo performances and why such architectures can realize electricity outputs with no visible-light are discussed. Potential pathways and opportunities to enrich all-weather solar cell families are envisaged. The aspects discussed here may enable researchers to develop undiscovered abilities and to explore wide applications of advanced photovoltaics.

Come rain or shine! All-weather solar cells would trigger a photovoltaic revolutionary. In this article, we have outlined the design principles, working mechanisms, photovoltaic structures, proof-of-concepts experimental performances as well as potential pathways to all-weather solar cells.

The development of wearable and large-area fabric energy harvester and sensor has received great attention due to their promising applications in next-generation autonomous and wearable healthcare technologies. Here, a new type of “single” thread-based triboelectric nanogenerator (TENG) and its uses in elastically textile-based energy harvesting and sensing have been demonstrated. The energy-harvesting thread composed by one silicone-rubber-coated stainless-steel thread can extract energy during contact with skin. With sewing the energy-harvesting thread into a serpentine shape on an elastic textile, a highly stretchable and scalable TENG textile is realized to scavenge various kinds of human-motion energy. The collected energy is capable to sustainably power a commercial smart watch. Moreover, the simplified single triboelectric thread can be applied in a wide range of thread-based self-powered and active sensing uses, including gesture sensing, human-interactive interfaces, and human physiological signal monitoring. After integration with microcontrollers, more complicated systems, such as wireless wearable keyboards and smart beds, are demonstrated. These results show that the newly designed single-thread-based TENG, with the advantage of interactive, responsive, sewable, and conformal features, can meet application needs of a vast variety of fields, ranging from wearable and stretchable energy harvesters to smart cloth-based articles.

A new single-thread-based triboelectric nanogenerator (TENG) as well as related elastic and wearable large-area energy-harvesting textiles and various cloth-based applications are presented. The TENG with only one triboelectric thread can generate electricity from skin contact. The simplified structures will meet various application needs ranging from wearable and stretchable energy harvesting, self-powered active sensing, to various human-interactive uses.

Stretchable electrical interconnects based on serpentines combined with elastic materials are utilized in various classes of wearable electronics. However, such interconnects are primarily for direct current or low-frequency signals and incompatible with microwave electronics that enable wireless communication. In this paper, design and fabrication procedures are described for stretchable transmission line capable of delivering microwave signals. The stretchable transmission line has twisted-pair design integrated into thin-film serpentine microstructure to minimize electromagnetic interference, such that the line's performance is minimally affected by the environment in close proximity, allowing its use in thin-film bioelectronics, such as the epidermal electronic system. Detailed analysis, simulations, and experimental results show that the stretchable transmission line has negligible changes in performance when stretched and is operable on skin through suppressed radiated emission achieved with the twisted-pair geometry. Furthermore, stretchable microwave low-pass filter and band-stop filter are demonstrated using the twisted-pair structure to show the feasibility of the transmission lines as stretchable passive components. These concepts form the basic elements used in the design of stretchable microwave components, circuits, and subsystems performing important radio frequency functionalities, which can apply to many types of stretchable bioelectronics for radio transmitters and receivers.

The design of stretchable high-frequency transmission lines with twisted-pair geometry integrated into stretchable serpentines for wearable applications is presented. This transmission line that is in the form of ultrathin, conformal structure can transmit microwave frequency signals with low radio frequency and radiation losses, which is feasible as electrical interconnects for epidermal electronic systems requiring high-speed wireless communication capabilities.

Unusual cleavage of P−C and C−H bonds of the P₂N₂ ligand, in heteroleptic [Ni(P₂N₂)(diphosphine)]²⁺ complexes under mild conditions, results in the formation of an iminium formyl nickelate featuring a C,P,P-tridentate coordination mode. The structures of both the heteroleptic [Ni(P₂N₂)(diphosphine)]²⁺ complexes and the resulting iminium formyl nickelate have been characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. Density functional theory (DFT) calculations were employed to investigate the mechanism of the P−C/C−H bond cleavage, which involves C−H bond cleavage, hydride rotation, Ni−C/P−H bond formation, and P−C bond cleavage.

Cut and paste: Heteroleptic [Ni(P₂N₂)(disphosphine)] complexes undergo facile cleavage of P−C and C−H bonds in the P₂N₂ ligand at room temperature, forming P−H and Ni−C bonds in the resulting iminium formyl nickelate complexes featuring a C,P,P-tridentate coordination mode. Density functional theory (DFT) calculations were employed to investigate the mechanism of the P−C/C−H bond cleavage.

Single-walled carbon nanotubes (SWNTs)/polyaniline (PANI) composite films with enhanced thermoelectric properties were prepared by combining in situ polymerization and solution processing. Conductive atomic force microscopy and X-ray diffraction measurements confirmed that solution processing and strong π–π interactions between the PANI and SWNTs induced the PANI molecules to form a highly ordered structure. The improved degree of order of the PANI molecular arrangement increased the carrier mobility and thereby enhanced the electrical transport properties of PANI. The maximum in-plane electrical conductivity and power factor of the SWNTs/PANI composite films reached 1.44×10³ S cm⁻¹ and 217 μW m⁻¹ K⁻², respectively, at room temperature. Furthermore, a thermoelectric generator fabricated with the SWNTs/PANI composite films showed good electric generation ability and stability. A high power density of 10.4 μW cm⁻² K⁻¹ was obtained, which is superior to most reported results obtained in organic thermoelectric modules.

PANI for your thoughts: Single-walled carbon nanotubes (SWNTs)/polyaniline (PANI) composite films with enhanced thermoelectric properties are prepared by combining in situ polymerization and solution processing. Strong π–π interactions induce the PANI molecules to form a highly ordered structure, which improves carrier mobility and thereby enhances electrical transport.

Vertical and in-plane heterostructures based on van der Waals (vdW) crystals have drawn rapidly increasing attention owning to the extraordinary properties and significant application potential. However, current heterostructures are mainly limited to vdW crystals with a symmetrical hexagonal lattice, and the heterostructures made by asymmetric vdW crystals are rarely investigated at the moment. In this contribution, it is reported for the first time the synthesis of layered orthorhombic SnS–SnS_xSe_(1−x) core–shell heterostructures with well-defined geometry via a two-step thermal evaporation method. Structural characterization reveals that the heterostructures of SnS–SnS_xSe_(1−x) are in-plane interconnected and vertically stacked, constructed by SnS_xSe_(1−x) shell heteroepitaxially growing on/around the pre-synthesized SnS flake with an epitaxial relationship of (303)_SnS//(033)_{SnSxSe(1−x)}, [010]_SnS//[100]_{SnSxSe(1−x)}. On the basis of detailed morphology, structure and composition characterizations, a growth mechanism involving heteroepitaxial growth, atomic diffusion, as well as thermal thinning is proposed to illustrate the formation process of the heterostructures. In addition, a strong polarization-dependent photoresponse is found on the device fabricated using the as-prepared SnS−SnS_xSe_(1−x) core–shell heterostructure, enabling the potential use of the heterostructures as functional components for optoelectronic devices featured with anisotropy.

Layered orthorhombic SnS–SnS_xSe_(1−x) core–shell heterostructures are successfully synthesized via an epitaxial growth method. Due to the structural characteristic of the components, the heterostructures are able to show a strong polarization-dependent photoresponse, which will facilitate developing novel functional optoelectronic devices beyond conventional materials.

Currently, a broad interdisciplinary research effort is pursued on biomedical applications of 2D materials (2DMs) beyond graphene, due to their unique physicochemical and electronic properties. The discovery of new 2DMs is driven by the diverse chemical compositions and tuneable characteristics offered. Researchers are increasingly attracted to exploit those as drug delivery systems, highly efficient photothermal modalities, multimodal therapeutics with non-invasive diagnostic capabilities, biosensing, and tissue engineering. A crucial limitation of some of the 2DMs is their moderate colloidal stability in aqueous media. In addition, the lack of suitable functionalisation strategies should encourage the exploration of novel chemical methodologies with that purpose. Moreover, the clinical translation of these emerging materials will require undertaking of fundamental research on biocompatibility, toxicology and biopersistence in the living body as well as in the environment. Here, a thorough account of the biomedical applications using 2DMs explored today is given.

Different classes of two-dimensional materials are emerging as biomaterial alternatives to graphene due to their unique physicochemical properties and their good biocompatibility. Currently, applications including anticancer therapeutics, multimodal bioimaging, cancer theranostics, biosensing, tissue engineering, and antimicrobial coatings are explored. However, there are still several concerns and new challenges ahead of these materials before their translation into clinical use.

Simple modification of benzo[h]benz[5,6]acridino[2,1,9,8-klmna]acridine-8,16-dione, an old and almost-forgotten vat dye, by reduction of its carbonyl groups and subsequent O-alkylation, yields solution-processable, electroactive, conjugated compounds of the periazaacene type, suitable for the use in organic electronics. Their electrochemically determined ionization potential and electron affinity of about 5.2 and −3.2 eV, respectively, are essentially independent of the length of the alkoxyl substituent and in good agreement with DFT calculations. The crystal structure of 8,16-dioctyloxybenzo[h]benz[5,6]acridino[2,1,9,8-klmna]acridine (FC-8), the most promising compound, was solved. It crystallizes in space group P and forms π-stacked columns held together in the 3D structure by dispersion forces, mainly between interdigitated alkyl chains. Molecules of FC-8 have a strong tendency to self-organize in monolayers deposited on a highly oriented pyrolytic graphite surface, as observed by STM. 8,16-Dialkoxybenzo[h]benz[5,6]acridino[2,1,9,8-klmna]acridines are highly luminescent, and all have photoluminescence quantum yields of about 80 %. They show efficient electroluminescence, and can be used as guest molecules with a 4,4′-bis(N-carbazolyl)-1,1′-biphenyl host in guest/host-type organic light-emitting diodes. The best fabricated diodes showed a luminance of about 1900 cd m⁻¹², a luminance efficiency of about 3 cd A⁻¹, and external quantum efficiencies exceeding 0.9 %.

New life for an old dye: Simple modification of flavanthrone, an old, intractable, and almost-forgotten vat dye, by reduction of its carbonyl groups to phenolates followed by O-alkylation, gave a new group of solution-processable, electroactive, conjugated compounds (see figure). Their HOMO and LUMO energies, as well as their ionization potentials and electron affinities, make them suitable for application as components of organic light-emitting diodes.