Facile and Unplugged Surface Plasmon Resonance Biosensor with NIR-Emitting Perovskite Nanocomposites for Fast Detection of SARS-CoV-2.

The emergence of the coronavirus disease 2019 (COVID-19) pandemic prompted researchers to develop portable biosensing platforms, anticipating to detect the analyte in a label-free, direct, and simple manner, for deploying on site to prevent the spread of the infectious disease. Herein, we developed a facile wavelength-based SPR sensor built with the aid of a 3D printing technology and synthesized air-stable NIR-emitting perovskite nanocomposites as the light source. The simple synthesis processes for the perovskite quantum dots enabled low-cost and large-area production and good emission stability. The integration of the two technologies enabled the proposed SPR sensor to exhibit the characteristics of lightweight, compactness, and being without a plug, just fitting the requirements of on-site detection. Experimentally, the detection limit of the proposed NIR SPR biosensor for refractive index change reached the 10-6 RIU level, comparable with that of state-of-the-art portable SPR sensors. In addition, the bio-applicability of the platform was validated by incorporating a homemade high-affinity polyclonal antibody toward the SARS-CoV-2 spike protein. The results demonstrated that the proposed system was capable of discriminating between clinical swab samples collected from COVID-19 patients and healthy subjects because the used polyclonal antibody exhibited high specificity against SARS-CoV-2. Most importantly, the whole measurement process not only took less than 15 min but also needed no complex procedures or multiple reagents. We believe that the findings disclosed in this work can open an avenue in the field of on-site detection for highly pathogenic viruses.

A Study of High-Sensitivity Electro-Resistance Type Pre-Annealing ZnO-Doped CsPbBr3 Perovskite Acetone Sensors.

In this work, acetone gas sensors were fabricated using pre-annealing metal oxide zinc oxide (pa-ZnO)-doped perovskite cesium lead bromide (CsPbBr3). The ZnO nanopowder, before it was doped into CsPbBr3 solution, was first put into a furnace to anneal at different temperatures, and formed the pa-ZnO. The properties of pa-ZnO were different from ZnO. The optimized doping conditions were 2 mg of pa-ZnO nanopowder and pre-annealing at 300 °C. Under these conditions, the highest sensitivity (gas signal current-to-air background current ratio) of the ZnO-doped CsPbBr3 perovskite acetone sensor was 1726. In addition, for the limit test, 100 ppm was the limit of detection of the ZnO-doped CsPbBr3 perovskite acetone sensor and the sensitivity was 101.

Two-Dimensional (PEA)2PbBr4 Perovskites Sensors for Highly Sensitive Ethanol Vapor Detection.

Two-dimensional (2D) perovskite have been widely researched for solar cells, light-emitting diodes, photodetectors because of their excellent environmental stability and optoelectronic properties in comparison to three-dimensional (3D) perovskite. In this study, we demonstrate the high response of 2D-(PEA)2PbBr4 perovskite of the horizontal vapor sensor was outstandingly more superior than 3D-MAPbBr3 perovskite. 2D transverse perovskite layer have the large surface-to-volume ratio and reactive surface, with the charge transfer mechanism, which was suitable for vapor sensing and trapping. Thus, 2D perovskite vapor sensors demonstrate the champion current response ratio R of 107.32 under the ethanol vapors, which was much faster than 3D perovskite (R = 2.92).

Very Low-Efficiency Droop in 293 nm AlGaN-Based Light-Emitting Diodes Featuring a Subtly Designed p-Type Layer.

This paper reports an AlGaN-based ultraviolet-B light-emitting diode (UVB-LED) with a peak wavelength at 293 nm that was almost free of efficiency droop in the temperature range from 298 to 358 K. Its maximum external quantum efficiencies (EQEs), which were measured at a current density of 88.6 A cm-2, when operated at 298, 318, and 338 K were 2.93, 2.84, and 2.76%, respectively; notably, however, the current droop (J-droop) in each of these cases was less than 1%. When the temperature was 358 K, the maximum EQE of 2.61% occurred at a current density of 63.3 A cm-2, and the J-droop was 1.52%. We believe that the main mechanism responsible for overcoming the J-droop was the uniform distribution of the concentrations of injected electrons and holes within the multiple quantum wells. Through the subtle design of the p-type AlGaN layer, with the optimization of the composition and doping level, the hole injection efficiency was enhanced, and the Auger recombination mechanism was inhibited in an experimental setting.

The Effects of Temperature on the Growth of a Lead-Free Perovskite-Like (CH3NH3)3Sb2Br9 Single Crystal for An MSM Photodetector Application.

We have fabricated a photodetector based on (CH3NH3)3Sb2Br9 (MA3Sb2Br9) lead-free perovskite-like single crystal, which plays an important role in the optoelectronic characteristics of the photodetector as a perovskite-like photosensitive layer. Here, MA3Sb2Br9 single crystals were synthesized by an inverse temperature crystallization process with a precursor solution at three different growth temperatures, 60 °C, 80 °C, and 100 °C. As a result, a MA3Sb2Br9 single crystal with an optimum growth temperature of 60 °C presented a low trap density of 2.63 × 1011 cm-3, a high charge carrier mobility of 0.75 cm2 V-1 s-1, and excellent crystal structure and optical absorption properties. This MA3Sb2Br9 perovskite-like photodetector displayed a low dark current of 8.09 × 10-9 A, high responsivity of 0.113 A W-1, and high detectivity of 4.32 × 1011 Jones.

Preparation and Characterization of Thin-Film Solar Cells with Ag/C60/MAPbI3/CZTSe/Mo/FTO Multilayered Structures.

New solar cells with Ag/C60/MAPbI3/Cu2ZnSnSe4 (CZTSe)/Mo/FTO multilayered structures on glass substrates have been prepared and investigated in this study. The electron-transport layer, active photovoltaic layer, and hole-transport layer were made of C60, CH3NH3PbI3 (MAPbI3) perovskite, and CZTSe, respectively. The CZTSe hole-transport layers were deposited by magnetic sputtering, with the various thermal annealing temperatures at 300 °C, 400 °C, and 500 °C, and the film thickness was also varied at 50~300 nm The active photovoltaic MAPbI3 films were prepared using a two-step spin-coating method on the CZTSe hole-transport layers. It has been revealed that the crystalline structure and domain size of the MAPbI3 perovskite films could be substantially improved. Finally, n-type C60 was vacuum-evaporated to be the electronic transport layer. The 50 nm C60 thin film, in conjunction with 100 nm Ag electrode layer, provided adequate electron current transport in the multilayered structures. The solar cell current density-voltage characteristics were evaluated and compared with the thin-film microstructures. The photo-electronic power-conversion efficiency could be improved to 14.2% when the annealing temperature was 500 °C and the film thickness was 200 nm. The thin-film solar cell characteristics of open-circuit voltage, short-circuit current density, fill factor, series-resistance, and Pmax were found to be 1.07 V, 19.69 mA/cm2, 67.39%, 18.5 Ω and 1.42 mW, respectively.

Study of Metal-Semiconductor-Metal CH3NH3PbBr3 Perovskite Photodetectors Prepared by Inverse Temperature Crystallization Method.

Numerous studies have addressed the use of perovskite materials for fabricating a wide range of optoelectronic devices. This study employs the deposition of an electron transport layer of C60 and an Ag electrode on CH3NH3PbBr3 perovskite crystals to complete a photodetector structure, which exhibits a metal-semiconductor-metal (MSM) type structure. First, CH3NH3PbBr3 perovskite crystals were grown by inverse temperature crystallization (ITC) in a pre-heated circulator oven. This oven was able to supply uniform heat for facilitating the growth of high-quality and large-area crystals. Second, the different growth temperatures for CH3NH3PbBr3 perovskite crystals were investigated. The electrical, optical, and morphological characteristics of the perovskite crystals were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy, and photoluminescence (PL). Finally, the CH3NH3PbBr3 perovskite crystals were observed to form a contact with the Ag/C60 as the photodetector, which revealed a responsivity of 24.5 A/W.

Post-hot-cast annealing deposition of perovskite films with infused multifunctional organic molecules to enhance the performance of large-area light-emitting devices.

All-inorganic perovskites show great promise as an emission layer in perovskite light-emitting diodes (PeLEDs) owing to their easy solution processing, low manufacturing cost, and excellent optoelectronic properties. However, there is still an immense performance gap from small-area devices to large-area PeLED devices. The inhomogeneity of large-area high-quality perovskite films inevitably leads to vast defects and electroluminescence performance losses. Herein, a post-hot-cast annealing deposition scheme and the introduction of the multifunctional molecule 2-amino-1,3-propanediol (APDO) were proposed to regulate the crystallization of the perovskite film. As a result, uniform APDO:CsPbBr2.5Cl0.5 perovskite films with high crystallinity and lower defect density were deposited by post-hot-cast annealing. A decent maximum brightness of 2659 cd m-2 was achieved for the large-area cyan PeLEDs with an emitting area of 400 mm2.

Buried Interface Passivation Using Organic Ammonium Salts for Efficient Inverted CsMAFA Perovskite Solar Cell Performance.

This study uses different doping ratios of CsCl and MACl dual additives to improve the quality of the perovskite, where CsCl reduces the perovskite trap density and increases the resistance of charge recombination, and MACl was used to improve the phase stability. Finally, the composition of Cs0.1MA0.09FA0.81PbCl0.14I2.86 perovskite solar cell (PeSC) can achieve better open-circuit voltage (Voc), short-circuit current density (Jsc), and photoelectric conversion efficiency (PCE). To achieve a better PCE of PeSC, the use of organic ammonium salt butane-1,4-diammonium iodide (BDAI2) to passivate the perovskite bottom surface (buried interface) can effectively suppress the formation of defects at the perovskite buried interface, obtain higher crystallinity, and thereby reduce the probability of carrier recombination. The Jsc, fill factor (FF), and PCE of the PeSC based on BDAI2 passivation increased from 24.0 mA cm-2, 74.1%, and 18.6% to 24.5 mA cm-2, 79.9%, and 20.5%, respectively.

Improved stability and efficiency of inverted triple-cation mixed-halide perovskite solar cells with CsI-modified NiOx hole transporting layer.

Addressing the critical challenge of mitigating defect generation and enhancing the extended durability of perovskite solar cells (PeSCs) requires effective passivation materials. In our study, we investigated the impact of varying concentrations of cesium iodide (CsI), an alkali halide, on the interface layer among the hole transporting layer (HTL) and the perovskite film in a triple-cation lead hybrid halide Cs0.15FA0.81MA0.04Pb(I2.86Br0.14)3 perovskite layer. Our findings revealed that the introduction of CsI into the NiOx HTL led to improved crystallinity and a reduction in defects within the perovskite film. Consequently, the photovoltaic performance of the CsI-modified PeSC exhibited a notable enhancement. Specifically, the photoelectric conversion efficiency (PCE) increased from 18.7 % in the original PeSC, which lacked CsI modification, to 20.5 %. Moreover, this improvement in PCE was accompanied by excellent stability, with the CsI-modified PeSC retaining 80 % of its opening PCE even afterward 144 h of testing.

Stable Near-Infrared Photoluminescence of Hexagonal-Shaped PbS Nanoparticles with 1-Dodecanethiol Ligands.

In this study, lead(II) sulphide (PbS) nanoparticles of varying particle sizes were synthesized using the hot injection method, employing 1-octadecene (ODE) as a coordinating ligand in conjunction with oleylamine (OAm). This synthesis approach was compared with the preparation of hexagonal-shaped nanoparticles through the ligand of 1-Dodecanethiol (DT), resulting in DT-capped PbS nanoparticles. The prepared nanoparticles were characterized using multiple techniques including photoluminescence (PL), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR). The condensation reaction of DT ligands led to various nanoparticles within the range of 34.87 nm to 35.87 nm across different synthesis temperatures (120 °C, 150 °C, 180 °C, 210 °C, and 240 °C). The PbS with DT ligands exhibited a highly crystalline and superhydrophilic structure. Interestingly, near-infrared (NIR)-PL analysis revealed peaks at 1100 nm, representing the lowest-energy excitonic absorption peak of PbS nanoparticles for both ligands. This suggests their potential utility in various applications, including IR photoreactors, as well as in the development of non-toxic nanoparticles for potential applications in in vivo bioimaging.

Properties and alcohol sensing applications of quasi-2D (PEA)2(MA)3Sb2Br9 thin films.

We fabricated an alcohol detector based on (PEA)2(CH3NH3)3Sb2Br9 ((PEA)2MA3Sb2Br9) lead-free perovskite-like films. The XRD pattern revealed that the (PEA)2MA3Sb2Br9 lead-free perovskite-like films exhibited a quasi-2D structure. The optimal current response ratios are 74 and 84 for 5 and 15% alcohol solutions, respectively. When the amount of PEABr decreases in the films, the conductivity of the sample in ambient alcohol with a high alcohol concentration solution increases. The alcohol was dissolved into water and carbon dioxide due to the catalyst effect of the quasi-2D (PEA)2MA3Sb2Br9 thin film. The rise and fall times for the alcohol detector were 1.85 and 0.7 s, respectively, indicating that the detector was suitable.

Methylammonium halide salt interfacial modification of perovskite quantum dots/triple-cation perovskites enable efficient solar cells.

Perovskite solar cells (PeSCs) have been introduced as a new photovoltaic device due to their excellent power conversion efficiency (PCE) and low cost. However, due to the limitations of the perovskite film itself, the existence of defects was inevitable, which seriously affects the number and mobility of carriers in perovskite solar cells, thus restricting PeSCs improved efficiency and stability. Interface passivation to improve the stability of perovskite solar cells is an important and effective strategy. Here, we use methylammonium halide salts (MAX, X = Cl, Br, I) to effectively passivate defects at or near the interface of perovskite quantum dots (PeQDs)/triple-cation perovskite films. The MAI passivation layer increased the open circuit voltage of PeQDs/triple-cation PeSC by 63 mV up to 1.04 V, with a high short-circuit current density of 24.6 mA cm-2 and a PCE of 20.4%, which demonstrated a significant suppression of interfacial recombination.

Fabrication and characteristics of ZnO/OAD-InN/PbPc hybrid solar cells prepared by oblique-angle deposition.

In this work, lead phthalocyanine (PbPc) and ZnO/InN inorganic semiconductor films prepared by oblique-angle deposition (OAD) were layered to form heterojunction organic/inorganic hybrid photovoltaic solar cells. Among the available organic materials, phthalocyanines, particularly the non-planar ones such as PbPc, are notable for their absorption in the visible and near infrared regions. The organic/inorganic hybrid solar cells fabricated on ZnO/OAD-InN/PbPc showed short-circuit current density (J(SC)), open-circuit voltage (V(OC)), and power conversion efficiencies (η) of 1.2 mA/cm², 0.6 V and 0.144%, respectively.

Organic and Polymeric Thin-Film Materials for Solar Cells: A New Open Special Issue in Materials.

"Organic and Polymeric Thin-Film Materials for Solar Cells" is a new open Special Issue of Materials [...].

Improved extraction efficiency of CsPbBr3 perovskite light-emitting diodes due to anodic aluminum oxide nanopore structure.

In this work, we investigate the improvement in the performance of a CsPbBr3 perovskite light-emitting diode (PeLED) due to an anodic aluminum oxide (AAO) nanopore structure. The AAO structure in the CsPbBr3 PeLED structure can improve the light extraction efficiency of CsPbBr3 PeLEDs in two ways: the emission light in the side direction being redirected to the normal direction due to the light scattering effect caused by aluminum oxide nanopores and the effective emission area as a result of the rough surface of the AAO structure. The peak luminance, current efficiency, and external quantum efficiency (EQE) were 11,460 cd/m2, 2.03 cd/A, and 0.69% at a bias of 6.0 V, respectively. For comparison, the luminance, current efficiency, and EQE values of CsPbBr3 PeLEDs with the AAO structure using 50 V of pore-expanding voltage demonstrated improvements of 282%, 190%, and 1280%, respectively, over CsPbBr3 PeLEDs without the AAO structure.

Efficient Perovskite Solar Cells via Phenethylamine Iodide Cation-Modified Hole Transport Layer/Perovskite Interface.

Perovskite solar cells (PeSCs) were fabricated by using Cs x FA1-x PbI3-x Cl x as the photoactive layer, and the effects of different proportions of cesium chloride (CsCl)/formamidinium iodide on perovskites were investigated. Cesium (Cs) can stabilize the α phase of the perovskite, while chlorine (Cl) can increase the size and crystallinity of perovskite crystals and reduce non-radiative cladding, thereby improving the performance of the overall device. The maximum power conversion efficiency (PCE) measured for Cs0.2FA0.8PbI2.8Cl0.2-based PeSCs was 18.9%. To further improve the photovoltaic characteristics of PeSCs, Cs0.2FA0.8PbI2.8Cl0.2-based PeSCs were introduced into different concentrations of phenethylammonium iodide (PEAI) to modify the interface between the NiO x hole transport layer (HTL) and the perovskite photoactive layer, which can simultaneously promote excellent crystallinity of the perovskite layer and passivated interfacial defects, reducing recombination near the perovskite/HTL interface in PeSCs, thereby increasing the efficiency of the device. Compared with the control Cs0.2FA0.8PbI2.8Cl0.2-based PeSC, the PCE of PeSC with the PEAI (10 mg/mL)-modified NiO x /perovskite interface increased significantly from 18.9 to 20.2%.

High-Performance Quasi-Two-Dimensional CsPbBr2.1Cl0.9:PEABr Perovskite Sky-Blue LEDs with an Interface Modification Layer.

This paper elucidates the increased luminescence efficiency of CsPbBr2.1Cl0.9 sky-blue perovskite light-emitting diodes (PeLEDs) achieved through the interface modification of 3,4 ethylenedioxythiophene (PEDOT):polystyrene sulfonic acid (PSS)/quasi-two-dimensional (QTD) perovskite using CsCl and CsBr materials, respectively. QTD films were fabricated using ratios of CsPbBr2.1Cl0.9 doped with phenethylamine hydrobromide (PEABr) at 60%, 80%, and 100%. The solvent dimethyl sulfide (C2H6OS) was employed under the excitation of ambient and 365-nm laser lights. The PeLED structure was composed of Al/LiF/2,2',2"-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi)/CsPbBr2.1Cl0.9:PEABr/interface modification layer/PEDOT:PSS/ITO glass. The optimized results revealed that the luminance, current efficiency, and external quantum efficiency of the QTD CsPbBr2.1Cl0.9:80% PEABr PeLED with the CsCl interface modification additive was 892 cd/m2, 3.87 cd/A, and 5.56%, respectively.

Effect of a Rubidium Chloride Carrier Confinement Layer on the Characteristics of CsPbBr3 Perovskite Light-Emitting Diodes.

This work describes the effect of a rubidium chloride (RbCl) interlayer in CsPbBr3 perovskite light-emitting diode (LED) structures. RbCl crystallites exhibited polyhedral structures and lattice parameters similar to those of CsPbBr3 perovskite crystallites. The lattice mismatch between the RbCl interlayer and CsPbBr3 active layer was only approximately 2%. The devices exhibited the best quality and performance when RbCl was used as the nucleation and carrier confinement layer. The crystallite sizes of CsPbBr3 with 0.2-, 0.5-, and 1-nm-thick RbCl bottom layers were 55.1, 65.4, and 55.1 nm, respectively. The full width at half maximum (FWHM) of the photoluminescence (PL) emission peak for CsPbBr3 with the RbCl bottom layer was 0.096 eV.

Aggregation Control, Surface Passivation, and Optimization of Device Structure toward Near-Infrared Perovskite Quantum-Dot Light-Emitting Diodes with an EQE up to 15.4.

In recent years, the performance of perovskite quantum dots (QDs) and QD-based light-emitting diodes (QLEDs) has improved greatly, with electroluminescence (EL) efficiency of green and red emission exceeding 20%. However, the development of perovskite near-infrared (NIR) QLEDs has reached stagnation, where the reported maximum EL efficiency is still below 6%, limiting their further applications. In this work, new NIR-emissive FAPbI3 QDs are developed by post-treating long alkyl-encapsulated QDs with 2-phenylethylammonium iodide (PEAI). The incorporation of PEAI reduces the QD surface defects for giving a high photoluminescence quantum yield up to 61.6%. The n-octane solution of PEAI-passivated FAPbI3 QDs is spin coated on top of the PEDOT:PSS-treated ITO electrode modified with a thermally crosslinked hole-transporting layer to give a full-coverage, smooth, and dense QD film. Incorporating with an effective electron-transporting material, CN-T2T, which has deep lowest unoccupied molecular orbital and good electron mobility, the optimal device with EL λmax at 772 nm achieves an external quantum efficiency up to 15.4% at a current density of 0.54 mA cm-2 (2.6 V), which is the highest efficiency ever reported for perovskite-based NIR QLEDs. This study provides a facile strategy to prepare high-quality perovskite QD films suitable for highly efficient NIR QLED applications.