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Computational spectrometers are explored to overcome the disadvantages of large size, narrow bandwidth and low spectral resolution suffered by conventional spectrometers. However, expensive spectral encoders and unstable algorithms impede widespread applications of the computational spectrometers. In this paper, we propose a neural network (NN)-based miniaturized spectrometer with a frosted glass as its spectral encoder. The frosted glass has the merits of easy fabrication, low loss, and high throughput. In order to evaluate the reconstruction ability, several frequently used algorithms such as the multilayer perceptron (MLP), convolutional neural network (CNN), residual convolutional neural network (ResCNN), and Tikhonov regularization are adopted to reconstruct different types of spectra in sequence. Experimental results show that the reconstruction performance of the MLP is better than other algorithms. By using the MLP network, the average mean squared error is 1.38 × 10 -3 and the reconstruction time is 16 µs. At the same time, a spectral resolution of 1.4 nm and a wavelength detection range of 420 nm-700 nm are realized. The effectiveness of this approach is also demonstrated by implementing a reconstruction for an unseen multi-peak spectrum. Equipped with the size, low cost, real time, broad-band, and high-resolution spectrometer, one may envision many portable wavelength analysis applications.

All-inorganic metal halide perovskite is promising for highly efficient and thermally stable perovskite light-emitting diodes (PeLEDs). However, there is still great room for improvement in the film quality, including low coverage and high trap density, which play a vital role in achieving high-efficiency PeLEDs. In this work, lead acetate (Pb(Ac) 2 ) was introduced into the perovskite precursor solution as an additive. Experimental results show that perovskite films deposited from a one-step anti-solvent free solution process with increased surface coverage and reduced trap density were obtained, leading to enhanced photoluminescence (PL) intensity. More than that, the valence band maximum (VBM) of perovskite films was reduced, bringing about a better energy level matching the work function of the hole-injection layer (HIL) poly (3,4-ethylenedioxythiophene)-poly (styrene sulfonate) (PEDOT: PSS), which is facilitated for the hole injection, leading to a decrease in the turn-on voltage (V th ) of PeLEDs from 3.4 V for the control device to 2.6 V. Finally, the external quantum efficiency (EQE) of the sky blue PeLEDs (at 484 nm) increased from 0.09% to 0.66%. The principles of Pb(Ac) 2 were thoroughly investigated by using X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). This work provides a simple and effective strategy for improving the morphology of perovskite and therefore the performance of PeLEDs.

Defects in perovskite films are one of the main factors that affect the efficiency and stability of halide perovskite solar cells (PSCs). Uncoordinated ions (such as Pb 2+ , I - ) act as trap states, causing the undesirable non-radiative recombination of photogenerated carriers. The formation of Lewis acid-base adducts in perovskite directly involves the crystallization process, which can effectively passivate defects. In this work, 4-(trifluoromethyl)-1H-imidazole (THI) was introduced into the perovskite precursor solution as a passivation agent. THI is a typical amphoteric compound that exhibits a strong Lewis base property due to its lone pair electrons. It coordinates with Lewis acid Pb 2+ , leading to the reduction in defect density and increase in crystallinity of perovskite films. Finally, the power conversion efficiency (PCE) of PSC increased from 16.49% to 18.97% due to the simultaneous enhancement of open-circuit voltage (V OC ), short circuit current density (J SC ) and fill factor (FF). After 30 days of storage, the PCE of the 0.16 THI PSC was maintained at 61.9% of its initial value, which was 44.3% for the control device. The working mechanism of THI was investigated. This work provides an attractive alternative method to passivate the defects in perovskite.

A π-conjugated small molecule N, N'-bis(naphthalen-1-yl)-N, N'-bis(phenyl)benzidine (NPB) was introduced into poly(9-vinylcarbazole) (PVK) as a hole transport layer (HTL) in inverted perovskite solar cells (PSCs). The NPB doping induces a better perovskite crystal growth, resulting in perovskite with a larger grain size and less defect density. Thus, the V OC , J SC, and FF of the PSC were all enhanced. Experimental results show that it can be ascribed to the reduction of surface roughness and improved hydrophilicity of the HTL. The effect of NPB on the aggregation of PVK was also discussed. This work demonstrates the great potential of PVK as the HTL of PSCs and provides an attractive alternative for HTL to realize high-efficiency PSCs.

Nonradiative recombination losses caused by defects in the perovskite layer seriously affects the efficiency and stability of perovskite solar cells (PSCs). Hence, defect passivation is an effective way to improve the performance of PSCs. In this work, trichloromelamine (TCM) was used as a defects passivator by adding it into the perovskite precursor solution. The experimental results show that the power conversion efficiency (PCE) of PSC increased from 18.87 to 20.15% after the addition of TCM. What's more, the environmental stability of PSCs was also improved. The working mechanism of TCM was thoroughly investigated, which can be ascribed to the interaction between the -NH- group and uncoordinated lead ions in the perovskite. This work provides a promising strategy for achieving highly efficient and stable PSCs.

Enhancing the injection of electron is an effective strategy to improve the performance of polymer light-emitting diodes (PLEDs). In this work, we reported a 286% improvement in current efficiency (CE) of PLEDs by using double-layered alkali halide electron injection layer (EIL) NaCl/LiF instead of LiF. A significant enhancement of electron injection was observed after inserting the NaCl layer. To understand the mechanism of such improvement, the devices with KBr/LiF and CsF/LiF as EILs were also investigated. Experimental results show that metal cation migrated under the effect of built-in electric field (V bi ), which plays the main role on the improvement of electron injection in PLEDs.

The morphology of perovskite light-absorption layer plays an important role in the performance of perovskite solar cells (PSCs). In this work, BiFeO 3 (BFO) nanostructures were used as additive for CH 3 NH 3 PbI 3 (MAPbI 3 ) via anti-solvent method. The addition of BFO nanostructures greatly enhanced the crystallinity, grain size and film uniformity of MAPbI 3 . As a result, the charge carrier mobility and electron diffusion length increased, leading to the increase of the short circuit current (J SC ) of PSCs. This work provides a very simple but effective approach to improve the morphology of perovskite layer for efficient PSCs.

The microbiota inhabiting the oral cavity is a complex ecosystem and responsible for resisting pathogens, maintaining homeostasis, and modulating the immune system. Some components of the oral microbiota contribute to the etiology of some oral diseases. Accumulating evidence suggests that the human oral microbiota is implicated in the development and progression of gastrointestinal cancer. In this review, we described the current understanding of possible roles and mechanisms of oral microbiota in the gastrointestinal cancers studied to date. The perspectives for oral microbiota as the biomarkers for early detection and new therapeutic targets were also discussed., Competing Interests: The authors report no conflicts of interest in this work.

The commonly used electron transport material (6,6)-phenyl-C61 butyric acid methyl ester (PCBM) for perovskite solar cells (PSC) with inverted planar structures suffers from properties such as poor film-forming. In this manuscript, we demonstrate a simple method to improve the film-forming properties of PCBM by doping PCBM with poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) as the electron transport layer (ETL), which effectively enhances the performance of CH₃NH₃PbI₃ based solar cells. With 5 wt % F8BT in PCBM, the short circuit current (J SC ) and fill factor (FF) of PSC both significantly increased from 17.21 ± 0.15 mA·cm -2 and 71.1 ± 0.07% to 19.28 ± 0.22 mA·cm -2 and 74.7 ± 0.21%, respectively, which led to a power conversion efficiency (PCE) improvement from 12.6 ± 0.24% to 15 ± 0.26%. The morphology investigation suggested that doping with F8BT facilitated the formation of a smooth and uniform ETL, which was favorable for the separation of electron-hole pairs, and therefore, an improved performance of PSC.

Uniform and dense perovskite films were realized by the one-step solution-processing method combined with toluene washing. The influence of the delay time applied for toluene washing on the film quality of CH 3 NH 3 PbI 3 (MAPbI 3 ) was investigated in a comprehensive manner. The optimal delay time was experimentally observed at the critical point when the color of the film changes from transparent to hazy. A detailed X-ray diffraction study suggested that such a color change was caused by the emergence of the MAPbI 3 crystal nucleus. This finding provides a convenient method to determine the optimal time accurately. With the optimal delay time, the most uniformly distributed MAPbI 3 grains with the largest average grain size and the smoothest surface were obtained. Owing to the realization of homogeneous MAPbI 3 films combined with full coverage of perovskite on the substrate achieved by toluene washing at the critical point, open-circuit voltage, short-circuit current, fill factor, and power conversion efficiency of 1.11 V, 18.24 mA/cm 2 , 77.47, and 15.54% were obtained., Competing Interests: The authors declare no competing financial interest.

The polar solvent dimethylformamide (DMF) was used to treat the emissive layer (EML) of polymer light-emitting diodes (PLEDs). The formation of a dipole layer at the EML/cathode interface after DMF treatment was proven, which led to a reduction of the electron-injection barrier. The dipole layer was formed mainly because of the intrinsic polarity of DMF. By control of the residue of DMF on the EML, a maximum enhancement of the peak luminous efficiency from 5.33 ± 0.57 to 12.05 ± 1.2 cd/A was achieved. This study suggests that solvent treatment is a simple and efficient approach to realizing highly efficient PLEDs with a high-work-function metal cathode.

This review presents an overall discussion on the morphology analysis and optimization for perovskite (PVSK) solar cells. Surface morphology and energy alignment have been proven to play a dominant role in determining the device performance. The effect of the key parameters such as solution condition and preparation atmosphere on the crystallization of PVSK, the characterization of surface morphology and interface distribution in the perovskite layer is discussed in detail. Furthermore, the analysis of interface energy level alignment by using X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy is presented to reveals the correlation between morphology and charge generation and collection within the perovskite layer, and its influence on the device performance. The techniques including architecture modification, solvent annealing, etc. were reviewed as an efficient approach to improve the morphology of PVSK. It is expected that further progress will be achieved with more efforts devoted to the insight of the mechanism of surface engineering in the field of PVSK solar cells.

One of the challenges toward electrically driven organic lasers is the huge optical loss associated with the contact of electrodes and organic gain medium in device. We demonstrated a significant reduction of the optical loss by using our newly developed conjugated polyelectrolytes (CPE) PPFN(+)Br(-) as interlayer between gain medium and electrode. The optically pumped amplified spontaneous emission (ASE) was observed at very low threshold for PFO as optical gain medium and up to 37 nm thick CPE as interlayer in device configuration, c.f., a 5.7-fold ASE threshold reduction from pump energy 150 μJ/cm(2) for ITO/PFO to 26.3 μJ/cm(2) for ITO/PPFN(+)Br(-)/PFO. Furthermore, ASE narrowing displayed at pump energy up to 61.8 μJ/cm(2) for device ITO/PEDOT:PSS/PFO/PPFN(+)Br(-)/Ag, while no ASE was observed for the reference devices without CPE interlayer at pump energy up to 240 μJ/cm(2). The optically pumped lasing operation has also been achieved at threshold up to 45 μJ/cm(2) for one-dimensional distributed feedback laser fabricated on ITO etched grating in devices with CPE interlayer, demonstrating a promising device configuration for addressing the challenge of electrically driven organic lasers.

We reported a simple and effective way of fabricating one-dimensional (1D) graphene oxide nanoscrolls (GONS) from graphene oxide (GO) sheets through shock cooling by liquid nitrogen. The corresponding mechanism of rolling was proposed. One possibility is the formation of ice crystals during the shock cooling process in liquid nitrogen to be the driving force. The other might be due to the uneven stress of the sheets inside or outside ice during the lyophilization. After reducing, graphene nanoscrolls (GNS) exhibited good structural stability, high specific surface area, and high specific capacitance. The capacitance properties were investigated by cyclic voltammetry, galvanostatic charge-discharge, and electrical impedance spectroscopy. A specific capacity of 156 F/g for the GNS at the current density of 1.0 A/g was obtained comparing with the specific capacity of 108 F/g for graphene sheets. Those results indicated that GNS-based rolling structure could be a kind of promising electrode material for supercapacitors and batteries.

In order to promote a polymer LED (PLED), we fabricated and introduced an ultrathin nickel oxide (NiO) buffer layer (<10 nm) between the indium tin oxide (ITO) anode and the poly (3, 4-ethylenedioxythiophene) hole injection layer in the PLED. The NiO buffer layer was easily formed on the ITO anode by electron-beam deposition of a nickel (Ni) metal source and an oxygen plasma treatment process. As a result, the PLED device with the NiO buffer layer on its ITO anode had the same turn-on voltage as conventional PLED devices without the NiO buffer layer, and the luminance of the PLED device with the NiO buffer layer was doubled, compared with the conventional PLED devices without the NiO buffer layer. Improvement of the optoelectronic performance of the PLED can be attributed to the increase of the current driven into the diode, resulting from the NiO buffer layer, which can enhance the hole injection and balance the injection of the two types of carriers (holes and electrons). Thus it is an excellent choice to introduce the NiO buffer layer onto the ITO anode of the PLED devices in order to enhance the optoelectronic performance of PLED devices.

A simple and robust process has been developed to control the growth of the organic nanowires in situ self-assembled in a polymer matrix, lift off the nanostructure/polymer composite film from the mother substrate for storage and transfer, and remove the polymer host prior to usage. Every step was completed through a solution process, which ensured the process's simplicity and low cost. The realization of large-sized nanowire/polymer composite film demonstrated the necessary process scalability required by the industrial roll-to-roll manufacturing.

Efficient green phosphorescent polymer light-emitting diodes (PLED) based on aluminum (Al) cathode were demonstrated. The device composed of neutral aminoalkyl substituted polyfluorene, poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) as the host and an Ir complex, fac-tris(2-(4-tert-butyl)-phenylpyridine)iridium (Ir(Bu-PPy)(3)), as the dopant. High luminous efficiency of 35.7 cd/A and a luminance of more than 10 000 cd/m(2) were obtained. The device performance was comparable to those of the devices from (Ir(Bu-PPy)(3)), doped into PVK as the host with a low work-function metal as cathode (such as barium and calcium). We found out that the high-performance was due to the effective electron injection from PFN/Al bilayer cathode, improved charge balance as well as significant reduction of back-transfer of excitons from Ir complex to the low-lying PFN triplet level in the PVK/PFN interface.