Efficient low-grade heat recovery can help to reduce greenhouse gas emission as over 70% of primary energy input is wasted as heat, but current technologies to fulfill the heat-to-electricity ...conversion are still far from optimum. Here we report a direct thermal charging cell, using asymmetric electrodes of a graphene oxide/platinum nanoparticles cathode and a polyaniline anode in Fe
/Fe
redox electrolyte via isothermal heating operation. When heated, the cell generates voltage via a temperature-induced pseudocapacitive effect of graphene oxide and a thermogalvanic effect of Fe
/Fe
, and then discharges continuously by oxidizing polyaniline and reducing Fe
under isothermal heating till Fe
depletion. The cell can be self-regenerated when cooled down. Direct thermal charging cells attain a temperature coefficient of 5.0 mV K
and heat-to-electricity conversion efficiency of 2.8% at 70 °C (21.4% of Carnot efficiency) and 3.52% at 90 °C (19.7% of Carnot efficiency), outperforming other thermoelectrochemical and thermoelectric systems.
The photovoltaic performance of perovskite solar cells is highly dependent on the control of morphology and crystallization of perovskite film, which usually requires a controlled atmosphere. ...Therefore, fully ambient fabrication is a desired technology for the development of perovskite solar cells toward real production. Here, an air‐knife assisted recrystallization method is reported, based on a simple bath‐immersion to prepare high‐quality perovskite absorbers. The resulted film shows a strong crystallinity with pure domains and low trap‐state density, which contribute to the device performance and stability. The proposed method can operate in a wide process window, such as variable relative humidity and bath‐immersion conditions, demonstrating a power conversion efficiency over 19% and 27% under 1 sun and 500–2000 lux dim‐light illumination respectively, which is among the highest performance of ambient‐process perovskite solar cells.
An air knife–assisted recrystallization method is developed to fabricate high‐quality perovskite film in air under daily variable weather. The presented method is a root fabrication based on a bath‐immersion process, offering useful insights for fabricating highly efficient ambient‐process perovskite solar cells toward real production and paves a way for dim‐light harvesting and recycling.
Ionic circuits using ions as charge carriers have demonstrated great potential for flexible and bioinspired electronics. The emerging ionic thermoelectric (iTE) materials can generate a potential ...difference by virtue of selective thermal diffusion of ions, which provide a new route for thermal sensing with the merits of high flexibility, low cost, and high thermopower. Here, ultrasensitive flexible thermal sensor arrays based on an iTE hydrogel consisting of polyquaternium‐10 (PQ‐10), a cellulose derivative, as the polymer matrix and sodium hydroxide (NaOH) as the ion source are reported. The developed PQ‐10/NaOH iTE hydrogel achieves a thermopower of 24.17 mV K−1, which is among the highest values reported for biopolymer‐based iTE materials. The high p‐type thermopower can be attributed to thermodiffusion of Na+ ions under a temperature gradient, while the movement of OH− ions is impeded by the strong electrostatic interaction with the positively charged quaternary amine groups of PQ‐10. Flexible thermal sensor arrays are developed through patterning the PQ‐10/NaOH iTE hydrogel on flexible printed circuit boards, which can perceive spatial thermal signals with high sensitivity. A smart glove integrated with multiple thermal sensor arrays is further demonstrated, which endows a prosthetic hand with thermal sensation for human–machine interaction.
This work demonstrates ultrasensitive flexible thermal sensor arrays based on the polyquaternium‐10/NaOH ionic thermoelectric (iTE) hydrogel. The selective thermal diffusion of ions in the iTE hydrogel leads to a high thermopower of 24.17 mV K−1. The thermal sensor array is able to perceive spatial thermal signals with high sensitivity, which endows a prosthetic hand with thermal sensation for human–machine interaction.
Deterministic integration of arbitrary semiconductor heterostructures opens a new class of modern electronics and optoelectronics. However, the realization of such heterostructures continues to ...suffer from impracticality, requiring energy‐ and labor‐intensive, time‐consuming fabrication processes. Here a 3D printing approach to fabricate freestanding metal halide perovskite nanowire heterostructures with a high degree of control over shape and composition is demonstrated. These features arise from freeform guiding of evaporation‐driven perovskite crystallization by a femtoliter precursor meniscus formed on a printing nozzle. By using a double‐barreled nanopipette as a printing nozzle, “all‐at‐once” heterostructure fabrication is achieved within seconds. The 3D‐printed perovskite nanowire heterojunctions with multiple emission colors provide exciting optical functionalities such as programmable color mixing and encryption at the single nanopixel level. This “lithography‐free” additive approach opens up the possibility to freely design and realize heterostructure‐based devices without the constraints of traditional manufacturing processes.
“All‐at‐once” 3D printing of perovskite nanowire heterostructures with programmed shape and composition is realized within seconds by using a dual‐nano‐nozzle. The 3D‐printed, freestanding perovskite nanowire heterojunctions with multiple emission colors provide exciting optical functionalities such as programmable color mixing and encryption at the single nanopixel level for next‐generation display devices.
Inverted perovskite solar cells incorporating RF sputtered NiO thin films as a hole transport layer and window layer are demonstrated. The electrical and optical properties of the NiO thin films are ...engineered using varied sputtering conditions. The localized states within bandgap owing to its crystal disorder and nonstoichiometric features affect the transmittance and the optical bandgap of the NiO thin films which in turn influences the J
of the perovskite solar cells. In addition, the electrical properties of the NiO thin films can be also varied during sputtering condition affecting the concentration of nickel vacancies and the resulting hole concentration. The conductivity largely originates from the hole concentration relating to the density of states in the NiO thin films which influence the fill factor (FF) of the solar cells. The solar cells fabricated with the NiO thin films made at 4 Pa of deposition pressure show highest performance owing to excellent transmittance and wider bandgap along with moderate conductivity. With further optimization, the perovskite solar cells exhibit ~20 mA/cm
of J
and a 12.4% PCE (11.3% of averaged PCE).
Optically transparent wood has emerged as a promising glazing material. Thanks to the high optical transmittance, strong mechanical properties, and excellent thermal insulation capability of ...transparent wood, it offers a potential alternative to glass for window applications. Recently, thermo-, electro-, and photochromic transparent woods that dynamically modulate light transmittance have been investigated to improve building energy efficiency. However, it remains challenging to widely replace windows with transparent wood because of its poor weather resistance. In this study, an environment-friendly thermochromic transparent wood film (TTWF) with thermal switching of transmittance is proposed and demonstrated. To achieve thermochromism, the bleached wood is impregnated with the vanadium dioxide (VO2)/polyvinyl alcohol composite. Due to the self-densification of cellulose microfibrils during the evaporation of solvents, the transparent wood is in the form of thin films, which can be attached on the inner face of a window to protect it from severe weather conditions, making the installation convenient and low-cost. Furthermore, the surface of VO2-TTWF is modified by octadecyltrichlorosilane to enhance the waterproof ability and achieve self-cleaning and antidust functions. The proposed VO2-TTWF shows great potential for application in energy-efficient buildings using sustainable materials with advanced optical properties (i.e., T lum = 50.5%, ΔT sol = 3.4%, and haze = 70%) that are mechanically robust (i.e., σ = 130.6 MPa along the wood growth direction), have low-thermal conductivity (i.e., K = 0.29 W m–1 K–1 along the perpendicular direction to the wood fibers), and demonstrate hydrophobic self-cleaning and antidust functions (i.e., contact angle: 121.9°). An experiment, using a model house, showed that the VO2-TTWF attached on the inner face of the window could significantly reduce the indoor air temperature by 33.9 °C compared with a bare glass panel, proving that VO2-TTWF has potential to be applied as a new-generation energy-efficient material for smart windows.
Solution‐processed 2D organic semiconductors (OSCs) have drawn considerable attention because of their novel applications from flexible optoelectronics to biosensors. However, obtaining well‐oriented ...sheets of 2D organic materials with low defect density still poses a challenge. Here, a highly crystallized 2,9‐didecyldinaphtho2,3‐b:2′,3′‐fthieno3,2‐bthiophene (C10‐DNTT) monolayer crystal with large‐area uniformity is obtained by an ultraslow shearing (USS) method and its growth pattern shows a kinetic Wulff's construction supported by theoretical calculations of surface energies. The resulting seamless and highly crystalline monolayers are then used as templates for thermally depositing another C10‐DNTT ultrathin top‐up film. The organic thin films deposited by this hybrid approach show an interesting coherence structure with a copied molecular orientation of the templating crystal. The organic field‐effect transistors developed by these hybrid C10‐DNTT films exhibit improved carrier mobility of 14.7 cm2 V−1 s−1 as compared with 7.3 cm2 V−1 s−1 achieved by pure thermal evaporation (100% improvement) and 2.8 cm2 V−1 s−1 achieved by solution sheared monolayer C10‐DNTT. This work establishes a simple yet effective approach for fabricating high‐performance and low‐cost electronics on a large scale.
Highly crystallized 2,9‐didecyldinaphtho2,3‐b:2′,3′‐fthieno3,2‐bthiophene (C10‐DNTT) monolayer crystal with large‐area uniformity is obtained by an ultraslow shearing method. This monolayer organic semiconductor thin film is used as the template for thermally evaporated upper C10‐DNTT film. The organic thin films deposited by this hybrid approach show an interesting coherence structure with a copied molecular orientation of the templating crystal.
Cu-Cu direct bonding has provided an alternative packaging method to circumvent various issues that arise in conventional Cu/Sn/Cu interconnects, and has potential applications in three-dimensional ...integrated circuits (3D IC). However, achieving a low-temperature bonding with high integrity remains a challenge. In this paper, we demonstrate a method of low-temperature Cu to Cu direct bonding with a perfectly indistinguishable bonding interface achieved using a randomly oriented nanocrystalline Cu interlayer at 250 °C. No orientation control is needed to be performed to assist bonding, neither any post-bonding annealing step is required. The elimination of the bonding interface was enabled by the low thermal stability of nanocrystalline Cu at low temperatures. Micro-scale tensile testing of the interfacial region has shown a ductile fracture behaviour which proves excellent mechanical integrity.
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•A synthesis of Nb-doped TiO2 nanoparticles for photoanode is developed.•The Nb-doping suppresses the surface recombination at TiO2-electrolyte interface.•The positive shift of ...conduction band minimum enhances the electron injection.•The DSSCs based on 2.0 mol% Nb-doped TiO2 achieve 18.9% improvement of efficiency.
The current co-hydrolysis used for the preparation of Nb-doped TiO2 starts from expensive and unstable niobium-based precursors, which is not suitable for mass production. In this paper, a scalable synthesis of Nb-doped TiO2 nanoparticles (NPs) made by mixing TiO2 paste with functionalized Nb2O5 sol gel is developed for the photoanodes in dye-sensitized solar cells (DSSCs). By doping Nb into TiO2, the positive shift of conduction band minimum (CBM) enhances the electron injection and the improved electron conductivity facilitates the electron transport, leading to an improved Jsc. In addition, the Nb-doping suppresses the surface recombination at TiO2-electrolyte interface, resulting in the increase of Voc. Therefore, the DSSCs based on 2.0mol% Nb-doped TiO2 photoanodes improve both Jsc and Voc to achieve 18.9% improvement of photoconversion efficiency as compared with the standard DSSCs. The DSSCs with Nb-doped TiO2 photoanode is also shown an improved long-term stability.
Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening adverse drug reactions characterized by massive epidermal necrosis, in which the specific danger signals ...involved remain unclear. Here we show that blister cells from skin lesions of SJS-TEN primarily consist of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, and both blister fluids and cells were cytotoxic. Gene expression profiling identified granulysin as the most highly expressed cytotoxic molecule, confirmed by quantitative PCR and immunohistochemistry. Granulysin concentrations in the blister fluids were two to four orders of magnitude higher than perforin, granzyme B or soluble Fas ligand concentrations, and depleting granulysin reduced the cytotoxicity. Granulysin in the blister fluids was a 15-kDa secretory form, and injection of it into mouse skin resulted in features mimicking SJS-TEN. Our findings demonstrate that secretory granulysin is a key molecule responsible for the disseminated keratinocyte death in SJS-TEN and highlight a mechanism for CTL- or NK cell-mediated cytotoxicity that does not require direct cellular contact.
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