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Residential fires are a significant risk factor threatening the health and security of occupants. The purpose of this study was to develop a novel fire-safety product to help occupants safely and quickly evacuate from fire. Residential fire-resistant clothing with an alterable robe-coverall structure was developed according to a functional design procedure. The protection and ergonomic performance of the new fire-resistant clothing were verified by material selection and testing, flame manikin testing, and a simulated evacuation test. The results demonstrated that the fire-resistant clothing could provide essential thermal protection, inhalation protection, tear resistant, and visibility. Moreover, compared to current fire blankets, this fire-resistant clothing integrated the robe and coverall together, providing improved thermal protection and ergonomics, while decreasing skin burn percentage by 30.04% and allowing flexible leg movement.

This study aimed to investigate the influence of wind speed and direction on the convective heat transfer from a sleeping infant in different postures. A computational fluid dynamics (CFD) model of a virtual infant manikin with realistic dimensions was developed to obtain the convective heat transfer coefficient (h

Older adults are at higher risk for fire-related injuries and deaths than younger people due to their impaired physical and sensory functions. However, current fire-safety products could not satisf...

Doping can improve the band alignment at the metal-semiconductor interface to modify the corresponding Schottky barrier, which is crucial for the realization of high-performance logic components. Here, we systematically investigated a convenient and effective method, ultraviolet ozone treatment, for p-type doping of MoTe2 field-effect transistors to enormously enhance the corresponding electrical performance. The resulted hole concentration and mobility are near 100 times enhanced to be ~ 1.0 × 1013 cm−2 and 101.4 cm2/(V·s), respectively, and the conductivity is improved by 5 orders of magnitude. These values are comparable to the highest ones ever obtained via annealing doping or non-lithographic fabrication methods at room temperature. Compared with the pristine one, the photoresponsivity (522 mA/W) is enhanced approximately 100 times. Such excellent performances can be attributed to the sharply reduced Schottky barrier because of the surface charge transfer from MoTe2 to MoOx (x < 3), as proved by photoemission spectroscopy. Additionally, the p-doped devices exhibit excellent stability in ambient air. Our findings show significant potential in future nanoelectronic and optoelectronic applications.

X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), atomic force microscopy (AFM) and X-ray diffraction (XRD) were applied to investigate the electronic structure and molecular packing of C8-BTBT on HOPG with an ultrathin C60 interlayer. It was found that C8-BTBT displays a Vollmer-Weber (V-W) growth mode on HOPG, with an ultrathin C60 interlayer (0.7 nm). Compared to the uniform lying-down growth mode as directly grown on HOPG, the C8-BTBT molecules here adopt a lying-down orientation at low coverage with some small tilt angles because the π-π interaction between C8-BTBT and HOPG is partly disturbed by the C60 interlayer, delivering a higher highest occupied molecular orbital (HOMO) in C8-BTBT. An interface dipole of 0.14 eV is observed due to electron transport from C8-BTBT to C60. The upward and downward band bending in C8-BTBT and C60, respectively, near the C8-BTBT/C60 interface reduces the hole transport barrier at the interface, facilitating the hole injection from C60 to C8-BTBT, while a large electron transfer barrier from C60 to C8-BTBT is detected at this interface, which effectively limits electron injection from C60 to C8-BTBT. The HOMO of C8-BTBT near the interface is largely lifted up by the C60 insertion layer, which causes a p-doping effect and increases the hole mobility in C8-BTBT. Furthermore, owing to the lowest occupied molecular orbital (LUMO) of C60 residing in the gap of C8-BTBT, charge transfer occurs between C60 and the trap states in C8-BTBT to effectively passivate the trapping states. Our efforts aid a better understanding of the electron structure and film growth of anisotropic molecules and provide a useful strategy to improve the performance of C8-BTBT-based devices.

The interface electronic structure between rubrene and permalloy (Ni80Fe20) has been studied by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). We find that the downward energy level bending at the rubrene/NiFe heterostructure is caused by the interaction between rubrene and NiFe at the interface. There is an interface dipole of 0.23 eV, pointing from NiFe to rubrene. Our researches deepen the understanding of the fundamentals and laid a foundation for the design of high-performance rubrene-based organic spintronic devices.

The electronic structure and surface composition of perovskite films after incorporation of different concentration of CsPbBr3 nanocrystals (NCs) have been investigated with ultraviolet photoelectron spectroscopy (UPS) and X-ray, and angle-resolved photoelectron spectroscopy (XPS, AR-XPS). The electronic structure, surface composition and morphology of perovskite film have been changed through the interaction between CsPbBr3 NCs and perovskite film. The band can be shifted upward by in incorporation of CsPbBr3 NCs and it is independent of the concentration of CsPbBr3 NCs. The surface component and its distribution can be adjusted by changing the concentration of CsPbBr3 NCs and the proper concentration of CsPbBr3 NCs would improve the stoichiometric ratio of perovskite film.

Atomically precise graphene nanoribbons (GNRs) can be on-surface synthesized from halogen containing molecular precursors. Here, we investigated the electronic structure evolution of 10,10′-dibromo-9,9′-bianthracene (DBBA), a famous precursor to 7-AGNRs, on both A u ( 111 ) and B i - 3 × 3 - A u ( 111 ) as a function of film thickness and post-annealing temperature using photoemission spectroscopy, low temperature scanning tunneling microscopy and density functional theories. No obvious changes in electronic structure of DBBA in three STM-observed configurations can be detected, indicating that nonplanar π -conjugated DBBA is physisorbed on both surfaces. The energy level alignments at the DBBA-substrate interfaces are demonstrated. Bismuth(Bi) insertion layer makes molecular−substrate interaction weaker, and makes the energy levels of DBBA thin film rigidly shift by ˜0.70 eV away from Fermi level, which enlarges the hole injection barrier and results in DBBA desorption at ˜470 K before dehalogenation occuring. The surface work function reduction can be explained by the push back effect and charge transfer induced interface dipole. Our findings explain why 7-GNRs could not be formed on B i - 3 × 3 - A u ( 111 ) .

The organic/inorganic semiconductor interfaces play a key role in determining the functionality of charge injection devices. The energy-level alignment at the interfaces between two in-plane organic materials (F16CuPc and CuPc) and single-crystal black phosphorus was systematically studied by in situ ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). In this work, we reveal that the deposition of F16CuPc onto black phosphorus surface leads to a considerable charge transfer across the interface, resulting in the pronounced increment of work function. As for the molecule–substrate interaction, both F16CuPc and CuPc interact with black phosphorus via van der Waals physisorption, as confirmed by the UPS and XPS measurements. Our results demonstrate the versatile use of organic molecules to tailor the energy levels of black phosphorus based hybrid structures, which can be potentially used to optimize its function in future devices.

The realization of p–n homojunctions, which can be achieved via spatially controlled carrier-type modulation, remains a challenge for two-dimensional transition metal dichalcogenides. Here, we report an effective method to tune intrinsic n-type few-layer MoSe2 to p-type through controlling precisely the ultraviolet-ozone treatment time, which can be attributed to the surface charge transfer from the underlying MoSe2 to MoOx (x < 3). The resulting hole mobility and concentration are ∼20.1 cm2 V−1 s−1 and ∼1.9 × 1012 cm−2, respectively, and the on–off ratio is ∼105, which are comparable to the values of pristine n-type MoSe2. Moreover, the lateral p–n homojunction prepared by partially treating MoSe2 displays a high rectification ratio of 2.4 × 104, an ideality factor of 1.1, and a high photoresponsivity of 0.23 A W−1 to the 633 nm laser at Vd = 0 V and Vg = 0 V due to the built-in potential in the p–n homojunction area. Our findings ensure the MoSe2 p–n diode as a promising candidate for future low-power operating photodevices.

Using lead phthalocyanine (PbPc) as surface doping material on black phosphorous (BP) we observe enhanced photo-excited carriers in the PbPc/BP heterostructure. The interfacial energy level alignment is investigated with ultra violet photoemission spectroscopy (UPS) and x-ray photoemission spectroscopy (XPS). The heterojunction is type I with gap of BP nested in that of PbPc, facilitating confinement of electrons and holes in BP. Ultrafast time-resolved two-photon photoemission (TR-2PPE) spectroscopy is used to study the influence of PbPc on the photo excited unoccupied electronic states and the dynamics of the relaxation processes. Monolayer PbPc can greatly increase the pump excited hot electrons and the 2 photon emission of BP. The enhanced population in the intermediate states is attributed to the straddling of the band alignment which benefits the photo excited electrons in PbPc transferring to BP. Density functional theory calculations supported the interface dipole and charge redistribution. Our results provide a fundamental understanding of the excellent opto-electrical response of PbPc/BP interface of promising application in the high efficient photo detectors.

The interfacial modification effect of the molybdenum trioxide (MoO3) buffer layer inserted between Al and black phosphorus (BP) was investigated with photoemission spectroscopy. The results show that MoO3 buffer layer can effectively prevent the destruction of the outermost BP lattice by Al thermal deposition and change the interface electronic structure between Al and BP. At the MoO3/BP interface, there is an interface dipole pointing from MoO3 to BP. During the metal deposition process, an interfacial chemical reaction between Al and MoO3 was found. These observations would provide insight for fabricating high-performance BP-based devices.

Ultraviolet-Ozone (UVO) treatment has potentially promoted the long-term stability and the high performance of two-dimensional-material-based devices. However, the detailed evolutions of materials upon UVO treatment are less reported and unclear. Herein, we have systematically investigated the evolutions of morphology and electronic properties of the UVO treated few-layered MoS2. A weak p-doping effect on a 1-hour-UVO-exposed bulk MoS2 is revealed by photoelectron spectroscopy, being attributed to the charge transfer from MoS2 to the newly-formed MoOx. Optical microscopy, atomic force microscopy, Raman and PL mapping measurements reveal an inhomogeneous change of MoS2 morphology after UVO treatment. The oxidation is initiated at intrinsic defect sites and dislocations, and then expands in-plane from dislocations to both sides to form one dimensional standing-wave-like features. The dangling-bond-free surface regions remain smooth, being attributed to the higher energetic barrier for O2 dissociation and chemisorption. A model is proposed to explain the mechanism of inhomogeneous oxidation. The rather different oxidation behavior of MoS2 compared with MoSe2 and MoTe2 can be attributed to the difference in the in-plane chemical bonds. Our findings remind that the device design with UVO oxidation need to take the microstructure changes after treatment into account instead of only taking notice of the doping effect for performance improvement.

The modification of C60 nano-interlayers on the organic field-effect transistors (OFETs) based on 2,7-diocty[1]benzothieno-[3,2-b]benzothiophene (C8-BTBT)/SiO2 was addressed at both the electronic structure and device level. It is observed that a band bending occurs in C8-BTBT layer with the insertion of C60, which induces a strong hole accumulation at the interface region, facilitating the formation of high concentration conducting channel when the interface is incorporated into OFETs. The strong acceptor C60 may cause charge transfer from the trap states in C8-BTBT, resulting in a field-effect operation with decreased threshold voltage. However, the increasing disorder in C8-BTBT induced by the C60 nano-interlayer may reduce the hole mobility at the C8-BTBT/SiO2 interface region and change the growth model of C8-BTBT. In addition, as confirmed by the transfer characteristic of the OFETs, the thin C60 insertion layer isn’t continuous enough to induce an ambipolar transport behavior despite its high mobility. The competition between the two opposite effects results in compromised performance in such OFETs. The device performance parameters deteriorate generally with increasing the C60 nano-interlayer thickness. So, it is inferred that the C60 interlayer alone cannot improve the performance of the C8-BTBT/SiO2-based OFETs without further optimization. Importantly, the device performance exhibits an abnormal improvement with a 6 nm C60 interlayer, which might be ascribed to a higher energy level shift of C8-BTBT caused by a quasi-continuous C60 film at this thickness.

X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), atomic force microscopy (AFM) and X-ray diffraction (XRD) were applied to investigate the electronic structure and molecular packing of C8-BTBT on HOPG with an ultrathin C

There is a significant correlation in organic semiconductor thin films between the morphology and electronic structure, and both have strong effects on device performance. In this presentation, we describe our investigations on the relationship of the morphology and corresponding electronic structure and electrical properties using scanning probe microscopy techniques, photoemission spectroscopy, and transport measurements on organic semiconductor thin films. We also present investigations on the effects on optoelectronic device performance especially after controlling the morphology by quasi-epitaxial growth on representative organic semiconductors.

The heteroepitaxial growth of fullerene (C60) on single-crystal black phosphorus (BP) has been studied using low-energy electron diffraction, X-ray and ultraviolet photoelectron spectroscopy, and density functional theory simulation. The occupied orbital features from C60 observed in the photoelectron spectra for C60/BP interface are slightly broadened at higher coverages of C60 and exhibit no direct evidence of hybridization, demonstrating that the C60/BP interaction is physisorption. Oxygen exposure of interface leads to obvious oxidation of BP in which C60 bridges the large electron-transfer barrier from BP to oxygen and plays an important role for the production of O2– and oxidation of BP. Our findings suggest that C60 does not form an ideal protection layer as the other n-type semiconductors. With the assistance of density functional theory calculations, the oxidized phosphorus at the interface prevents further charge transfer from BP to C60.

The interface electronic structure between Au and black phosphorus has been investigated with ultraviolet and X-ray photoemission spectroscopy. We observed that Au clusters form at the initial Au deposition, and an interface dipole is observed at the interface between Au and BP. The outermost BP lattice is destroyed and unbonded P appears, which is due to the formation of metallic Au by the deposition of more than 8 A Au. The unbonded P is surface segregated at 8–15 A, and it is covered with further increasing of the Au thickness. These observations reveal the processes in the Au/BP interface and provide possible directions to fabricate high performance Au/BP-based device.

Organic photomemory based on heterojunction phototransistor has been fabricated utilizing vanadyl-phthalocyanine (VOPc) on para-sexiphenyl (p-6P) thin films. Under 365 nm ultraviolet light irradiation, the ratio of photocurrent and dark current (Iph/Idark) and photoresponsivity of phototransistors are about 1.5×105 and 87 A/W, respectively. Such devices can transduce the input light signals into electrical signals and the output signals can be stored for recording the light simulation. After applying a light pulse (4.2 mW/cm2, 100 ms) on the device, the stored current level lasted for ~5000 s with only a 20% decrease, indicating a good photomemory behavior. Importantly, the photomemory behavior is effectively modulated by gate voltage. Multi-level photomemory behaviors are observed by modulating light pulse duration and light power intensity. Because of the construction of type-I heterojunction, the superior photomemory characteristics are mainly originated from efficient charge trapping at VOPc/p-6P inte...

The interfacial electronic structure and morphology of 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene(C8-BTBT) on polycrystalline Au film was investigated with photoemission spectroscopy (PES), atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXRD). The transport barriers of holes and electrons at the interface are 1.72 eV and 2.12 eV, respectively, from the UPS measurement. There is no chemical reaction of C8-BTBT with Au from the XPS investigation of core levels Au 4f, C 1s and S 2p. The upmost molecules adopt a standing up configuration deduced from the diffraction peaks in GIXRD and the step height in AFM. Increasing order of the upright orientation of C8-BTBT molecules with film growth result in decreasing work function of the C8-BTBT thin film by forming an outward pointing dipole layer with the ordered end C H bonds.

The interfacial electronic structure at the organic–inorganic semiconductor interface plays an important role in determining the electrical and optical performance of organic-based devices. Here, we studied the molecular alignment and electronic structure of thermally deposited 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) molecules on cleaved black phosphorus using photoelectron spectroscopy. The work function of black phosphorus is substantially upped with an organic thin film, originating from the charge transfer from black phosphorus to PTCDA. According to our photoemission spectrum and theoretical simulation, we also define the interaction between PTCDA and black phosphorus as weak van de Waals physisorption, rather than bonding chemisorption. Furthermore, we show that PTCDA thin film can effectively isolate reactive oxygen species, thereby protecting BP surface oxidation and deterioration under ambient conditions. Our results suggest the possibility of manipulating interfacial electronic str...

Modification by ultra-thin fullerene (C60) insertion layer of about 1 monolayer on the electronic structure and the film growth of 2,7-diocty[1]benzothieno-[3,2-b]benzothiophene (C8-BTBT) on silicon oxide (SiO2) is investigated using ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and X-ray diffraction (XRD). It is found that the ultra-thin C60 insertion layer doesn’t induce an ambipolar charge transport characteristic but it indeed lifts up the energy levels of C8-BTBT, resulting in p-doping and hole accumulation at the semiconductor-dielectric interface. The charge transfer from trap states residing in the band gap of C8-BTBT to the lowest unoccupied molecular orbital (LUMO) of C60 most likely leads to a decrease of threshold voltage for corresponding organic field effect transistors (OFETs) based on such a configuration. Band bending and decrease of the ionization potential (IP) are observed in the C8-BTBT film attributed to the increasing ordering of molecular orientation with the deposition of C8-BTBT. The HOMO downward shift is clearly bigger with the C60 insertion layer than that without. A typical Volmer-Weber (VW) growth mode is detected due to the weaker van der Waals interaction between C8-BTBT and the underlying layer of C60/C8-BTBT than that between the C8-BTBT molecules. Compared to without C60 interlayer, the molecular packing is a little more disordered at low coverages, resulting in more C8-BTBT molecules to lean away from the interface normal. The C8-BTBT film in such a structure phase has the HOMO closer to the EF than that at an almost perfectly vertically standing up configuration. Our results show that the introduction of C60 insertion layer lifts up the HOMO of C8-BTBT and improves the energy level alignment at the interface.

The realization of p-n homojunctions, which can be achieved via spatially controlled carrier-type modulation, remains a challenge for two-dimensional transition metal dichalcogenides. Here, we report an effective method to tune intrinsic n-type few-layer MoSe

Organic field-effect transistors (OFETs) based on organic semiconductor material 2,7-dioctyl[1]benzothieno[3,2- b ] benzothiophene (C8BTBT) as the active layer were fabricated by using organic molecular beam deposition (OMBD) and solution-processed methods, in which the C8BTBT thin-film morphology could be well controlled. In OMBD method, C8BTBT thin-film morphology could be controlled by the thickness of organic semiconductor layer and the deposition rate, of which the high-quality C8BTBT thin film was obtained at a thickness of about 20 nm and at a deposition rate of 1.2 nm/min, resulting in an obvious mobility improvement from 2.8 × 10 −3 cm 2 V −1 s −1 to 1.20 cm 2 V −1 s −1 . While in the solution-processing, C8BTBT thin-film morphology and thickness are related to the spin-coating speed and the substrate position in spin coater, i.e. , in-centre and off-centre position. The off-centre spin-coating with an optimized speed produced large-size domain C8BTBT thin film and accordingly resulted in a mobility of 1.47 cm 2 V −1 s −1 . Furthermore, an additive polystyrene (PS) was added into C8BTBT solution could further improve the thin-film morphology with more metal-stable phase as well as improve the interface contact with the substrate SiO 2 , resulting in the highest mobility up to 3.56 cm 2 V −1 s −1 . The research suggested that C8BTBT-based OFETs with the mobility over 1.20 cm 2 V −1 s −1 could be fabricated by using both OMBD and solution-processed methods through the thin-film morphology and structure optimization, which shows the potential applications in high-performance flexible and printed electronics.

The effect of a MoO3 buffer layer inserted between 2,7-dioctyl[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) and Co single-crystal film has been investigated using X-ray photoemission spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS). The high work function of the MoO3 buffer layer bends the electronic structure of C8-BTBT upward toward the interface, and thus reduces the hole injection barrier to 0.97 eV, facilitating the hole injection from the Co electrode to C8-BTBT via electron extraction from the highest occupied molecular orbital of C8-BTBT through the low-lying conduction band of MoO3. Desulfurization reaction of C8-BTBT by cobalt is also eliminated by the MoO3 buffer layer. These effects illustrate the significance of a MoO3 buffer layer on interface energy level alignment and provide important insight into device design, fabrication and possible direction to improve the performance of C8-BTBT/Co-based organic spin valves.

The electronic properties of the interface between Al and black phosphorus were studied by photoemission spectroscopy (PES). We observed that the growth pattern of Al deposited onto the BP film is Stranski-Krastanov mode. There is a reaction between Al atoms and P atoms at the interface and forming Al-P compounds, which changes the interface barriers and impedes carrier transfer. It is suggested that an inert buffer layer is necessary to protect BP and lower the carrier barriers to develop Al/BP-based device with high performance.

Black phosphorus (BP) has drawn extensive attention due to its unique semiconducting properties, but the poor stability of BP greatly limits its practical device application. In this work, we have fabricated a passivation layer of quasi-monolayer 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) on the BP simply by vacuum evaporation and annealing. The desirable air stability and strong interface charge transfer (ICT) of quasi-monolayer F4TCNQ/BP were confirmed with photoemission spectroscopy (PES) characterization. Density functional theory (DFT) calculations were also applied to further investigate the passivation mechanism, and the results show that the lone pair electrons in BP's valence band transfer to F4TCNQ molecules and were firmly localized due to the strong withdrawing ability of F4TCNQ, which greatly enhanced the energy barrier of electrons transfer to H2O and O2 and hindered the further oxidation of phosphorus atoms. Meanwhile, a nearly Ohmic contact is formed across the F4TCNQ/BP interface which may greatly facilitate the carrier transport in BP based devices.

We studied the electronic properties and spin polarization of the interface between Co and black phosphorus (BP) with ultraviolet, X-ray and spin-resolved photoemission spectroscopy. The results show that the outermost BP is destroyed and the unbonded P is produced in the process of Co deposition. There is no chemical reaction and an interface dipole is found at the Co/BP interface. The SR-UPS results show that there is an inverted spin polarization near EF and the spin polarization is about positive 10%, which is attributed to the interface hybridization between Co and BP.

The interface between organic semiconductors and Co thin film has been studied by spin-resolved photoemission spectroscopy. We found that the spin-polarized states of cobalt still exist when 1.0 nm rubrene or 0.7 nm C60 or 1.0 nm DBBA molecules deposited on Co, while 0.4 nm C8-BTBT eliminates the highly spin-polarized states of cobalt due to the desulfurization reaction occurred at the interface. The mode and strength of the interfacial interaction between organic semiconductors and magnetic electrode affect the spin-polarized states of magnetic electrode greatly. Our observations provide assistance in device design, fabrication and performance improvement in Co-based organic spintronic devices.

Pain-perceptual nociceptors (PPN) are essential sensory neurons that recognize harmful stimuli and can empower the human body to react appropriately and perceive precisely unusual or dangerous conditions in the real world. Furthermore, the sensitization-regulated nociceptors (SRN) can greatly assist pain-sensitive human to reduce pain sensation by normalizing hyperexcitable central neural activity. Therefore, the implementation of PPNs and SRNs in hardware using emerging nanoscale devices can greatly improve the efficiency of bionic medical machines by giving them different sensitivities to external stimuli according to different purposes. However, current most-normal organic/oxide transistors face a great challenge due to channel scaling, especially in the sub-10 nm channel technology. Here, a sub-10 nm indium-tin-oxide transistor with an ultrashort vertical channel as low as ≈3 nm, using sodium alginate bio-polymer electrolyte as gate dielectric, is demonstrated. This device can emulate important characteristics of PPN such as pain threshold, memory of prior injury, and pain sensitization/desensitization. Furthermore, the most intriguing character of SRN can be achieved by tuning the channel thickness. The proposed device can open new avenues for the fascinating applications of next-generation neuromorphic brain-like systems, such as bio-inspired electronic skins and humanoid robots.

Transient electronics, a new generation of electronics that can physically or functionally vanish on demand, are very promising for future “green” security biocompatible electronics. At the same time, hardware implementation of biological synapses is highly desirable for emerging brain-like neuromorphic computational systems that could look beyond the conventional von Neumann architecture. Here, a hardware-security physically-transient bidirectional artificial synapse network based on a dual in-plane-gate Al–Zn–O neuromorphic transistor was fabricated on free-standing laterally-coupled biopolymer electrolyte membranes (sodium alginate). The excitatory postsynaptic current, paired-pulse-facilitation, and temporal filtering characteristics from high-pass to low-pass transition were successfully mimicked. More importantly, bidirectional dynamic spatiotemporal learning rules and neuronal arithmetic were also experimentally demonstrated using two lateral in-plane gates as the presynaptic inputs. Most interestingly, excellent physically-transient behavior could be achieved with a superfast water-soluble speed of only ∼120 seconds. This work represents a significant step towards future hardware-security transient biocompatible intelligent electronic systems.

Comprehensive measurements of ultraviolet photoemission spectroscopy, X-ray photoemission spectroscopy, X-ray diffraction, and atomic force microscopy are adopted to investigate the corelevance of energy level alignment, molecular orientation, and film growth of Au/C8BTBT/perovskite interfaces. A small energy offset of valence band maximum of 0.06 eV between perovskite and C8BTBT makes hole transportation feasible. About 0.65 eV upward shift of energy levels is observed with the deposition of the Au film on C8BTBT, which enhances hole transportation to the Au electrode. The observations from the interface analysis are supported by a prototype photodetector of Au (80 nm)/C8BTBT (20 nm)/perovskite (100 nm) that exhibits excellent performances whose responsivity can reach up to 2.65 A W–1, 4 times higher than the best CH3NH3PbI3 photodetectors.

We have observed breaking down and reconstruction of islands in the film growth of a copper phthalocyanine (CuPc) film on highly ordered pyrolytic graphite using photoelectron spectroscopy (PES) and atomic force microscopy (AFM). At the initial deposition of CuPc, the film adopts the Stranski-Krastanov mode and the islands increase normally with the nominate film thickness. At a critical thickness around 6 nm, the islands break down suddenly into small clusters. Further deposition drives the reunion of clusters to form large islands again and makes the film coverage smaller at a nominate thickness of 13 nm. The nonmonotonic PES data and AFM morphology confirmed the re-exposure of the substrate and the first layer CuPc during the island reconstruction process. This nonmonotonic growth behavior may exist widely in many anisotropic molecular film growth processes where the thin film phases are confined or restricted by the symmetry of the substrate and different from their bulk phases.

Two dimensional atomic crystals, like grapheme (G) and molybdenum disulfide (MoS2), exhibit great interest in electronic and optoelectronic applications. The excellent physical properties, such as transparency, semiconductivity, and flexibility, make them compatible with current organic electronics. Here, we review recent progress in the understanding of the interfaces of van der Waals (vdW) heterostructures between small organic molecules (pentacene, copper phthalocyanine (CuPc), perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA), and dioctylbenzothienobenzothiophene (C8-BTBT)) and layered substrates (G, MoS2 and hexagonal boron nitride (h-BN)). The influences of the underlying layered substrates on the molecular arrangement, electronic and vibrational properties will be addressed.