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Solution-processed quasi-two-dimensional (quasi-2D) perovskites with self-assembled multiple quantum well (QW) structures exhibit enhanced exciton binding energy, which is ideal for use as light emitters. Here, we have found that postannealing is important to promoting the QWs' composition transfer, and we explored the correlation among the annealing time, the external quantum efficiency (EQE), and the operational stability of the device. During thermal annealing, the low-n QWs will gradually convert to high-n phases, accompanied by an increase in grain size. The EQE and working stability of the device exhibit different annealing-time dependences; that is, with the extension of the annealing time, the EQE gradually decreases while the working stability improves. By introducing trimethylolpropane trimethacrylate (TPTA) to passivate the emitting-region defects, the annealing-time dependence of the EQE was effectively eliminated due to the reduction of the nonradiative recombination rate, wherefore high efficiency and stability can be achieved simultaneously. Our research provides an effective way to develop highly efficiency and stable perovskite light-emitting diodes.

Quasi-2D perovskites have demonstrated great application potential in light-emitting diodes (LEDs). Defect passivation with chemicals plays a critical role to achieve high efficiency. However, there are still challenges in comprehensively passivating the defects distributed at surface, bulk, and buried interface of quasi-2D perovskite emitting films, hindering the further improvement of device performance. Herein, 9,9-substituted fluorene derivatives with different terminal functional groups are developed tactfully to realize comprehensive passivation, which greatly contributes to reducing nonradiative recombination at surface, suppressing ion migration in bulk, and filling interfacial charge traps at buried interface, respectively. Eventually, quasi-2D perovskite LEDs have an increased external quantum efficiency from 18.2% to 23.2%, improved operation lifetime by more than six times and lower turn-on voltage simultaneously. Here the importance of comprehensive passivation is highlighted and guidelines for the design and application of passivators for perovskite optoelectronics are provided.

Low-temperature solution-processed ZnO has decided advantages in flexible and tandem solar cells, while its application encountered difficulties in perovskite optoelectronic devices due to chemical instability at the ZnO–perovskite interface. It has been proven to be a result of protonation reaction between ZnO and organic cations in perovskite materials, thus accelerating the perovskite decomposition. Herein, considering this degradation mechanism, the enhanced interface stability is demonstrated by eliminating the deprotonization ability of ZnO with the modification of methylammonium chloride (MACl), even contacting it with high acidic MA-based perovskite (MAPbI3). After thermal stressing, the film appearance, light absorbance and crystal structure of MAPbI3 on the modified ZnO layer can maintain their initial states, and the long-term stability of MAPbI3-based perovskite solar cells (PSCs) is greatly strengthened. Meanwhile, for CsPbI2Br-based PSCs without organic cations, an improved efficiency not only reveals the foreseeable defect passivation effect of residual Cl but also certifies the great potential of the MACl modified ZnO layer in inorganic PSCs. This study overcomes the shortcomings of ZnO in PSCs comprising organic cations-based perovskite photoactive layer and provides an excellent candidate for a variety of other optoelectronic fields based on perovskite materials.

Organic–inorganic lead halide quasi-two-dimensional (2D) perovskites are promising gain media for lasing applications because of their low cost, tunable colour, excellent stability and solution processability1–3. Optically pumped continuous-wave (CW) lasing is highly desired for practical applications in high-density integrated optoelectronics devices and constitutes a key step towards electrically pumped lasers4–6. However, CW lasing has not yet been realized at room temperature because of the ‘lasing death’ phenomenon (the abrupt termination of lasing under CW optical pumping), the cause of which remains unknown. Here we study lead halide-based quasi-2D perovskite films with different organic cations and observe that long-lived triplet excitons considerably impede population inversion during amplified spontaneous emission and optically pumped pulsed and CW lasing. Our results indicate that singlet–triplet exciton annihilation is a possible intrinsic mechanism causing lasing death. By using a distributed-feedback cavity with a high quality factor and applying triplet management strategies, we achieve stable green quasi-2D perovskite lasers under CW optical pumping in air at room temperature. We expect that our findings will pave the way to the realization of future current-injection perovskite lasers. Lead halide-based quasi-two-dimensional perovskite films with different organic cations are used to create stable green lasers under continuous-wave optical pumping in air at room temperature.

Perovskites show exciting potential for photoelectric applications, especially for light-emitting diodes (LEDs), owing to their intrinsically high photoluminescence efficiency and color purity. Wit...

Additives play a critical role for efficient perovskite light-emitting diodes (PeLEDs). Here, we report a novel phosphonate/phosphine oxide dyad molecular additive (PE-TPPO), with unique dual roles of passivating defects and enhancing carrier radiative recombination, to boost the device efficiency of metal-halide perovskites. In addition to the defect passivation effect of the phosphine oxide group to enhance the photoluminescence intensity and homogeneity of perovskite film, the phosphonate group with strong electron affinity can capture the injected electrons to increase local carrier concentration and accelerate the carrier radiative recombination in the electroluminescence process. Owing to their synergistic enhancement on device efficiency, quasi-two-dimensional green PeLEDs modified by this dyad additive exhibit a maximum external quantum efficiency, current efficiency, and power efficiency of 25.1 %, 100.5 cd A

Emission thermal quenching is commonly observed in quasi-2D perovskite emitters, which causes the severe drop in luminescence efficiency for the quasi-2D perovskite light-emitting diodes (PeLEDs) during practical operations. However, this issue is often neglected and rarely studied, and the root cause of the thermal quenching has not been completely revealed now. Here, we develop a passivation strategy via the 2,7-dibromo-9,9-bis (3′-diethoxylphosphorylpropyl)-fluorene to investigate and suppress the thermal quenching. The agent can effectively passivate coordination-unsaturated Pb2+ defects of both surface and bulk of the film without affecting the perovskite crystallization, which helps to more truly demonstrate the important role of defects in thermal quenching. And our results reveal the root cause that the quenching will be strengthened by the defect-promoted exciton-phonon coupling. Ultimately, the PeLEDs with defect passivation achieve an improved external quantum efficiency (EQE) over 22% and doubled operation lifetime at room temperature, and can maintain about 85% of the initial EQE at 85 °C, much higher than 17% of the control device. These findings provide an important basis for fabricating practical PeLEDs for lighting and displays.

Due to the extremely inert surface of polyester (PET) fabric, a toxic and traditional resorcinol-formaldehyde-latex (RFL) dipping solution is always necessary in the rubber composite industry. Unfortunately, other effective methods for fabric surface treatment are in urgent need to improve the poor bonding interface between the fabric and the rubber matrix. In our study, a facile way to modify PET fabric was developed. Specifically, the fabric was treated by an alkaline solution and a coupling agent with magnetic agitation. Afterwards, the treated fabric/rubber composites were prepared through a co-vulcanization process. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and thermogravimetric analysis (TGA) were used to characterize the surface chemical composition of the modified fabrics. The adhesion behavior was analyzed by the peel test. The results showed that the fabric surface was successfully grafted with a coupling agent, and the peel strength reached 9.8 N/mm after KH550 treatment, which was an increase if 32% compared with that of the original fabric/rubber composite. In addition, the vulcanization rate and interfacial fracture mechanism are also researched.

The application of ZnO in the field of ultraviolet (UV) photodetectors is hindered by the lower responsivity, which is attributed to the strong band-to-band direct recombination caused by its large exciton binding energy and defect-assisted charge recombination related with the presence of defect states. Here, a solution-processed ZnO:Poly[N-9′-heptadecanyl-2,7- carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) composite photosensitive layer is employed to overcome these shortcomings. By incorporating PCDTBT, the localized built-in electric field can be constructed, which effectively facilitates the photogenerated exciton dissociation in annealing-free ZnO layer. Meanwhile, the formed depletion region in dark reduces the majority carrier density, thus decreasing the dark current of the photodetector. Furthermore, the absorption spectrum of PCDTBT perfectly overlaps the photoluminescence of ZnO, which is beneficial for the reutilization of carrier recombination energy by fluorescence resonance energy transfer. This study reveals that the charge recombination loss in ZnO limits the photoresponse, and points a direction to improve the light detection capacity of UV photodetectors.

The strong charge recombination such as defect-induced recombination in some transition metal oxide interlayers is really existent, which has resulted in the severe charge loss and the deteriorated device performance. Herein, the improved performance of a device is demonstrated with an annealing-free ZnO:P3HT composite interlayer by minimizing the charge recombination loss. The P3HT incorporated in the ZnO interlayer can reuse the wasted energy from the defect-induced charge radiative recombination by Forster resonance energy transfer, which will reduce the charge recombination loss in the device. Meanwhile, the highest occupied molecular orbital of P3HT than ZnO, can work as the hole traps in the ZnO interlayer, which also contributes to the increased background electron density and improved electron conductivity. The reduced charge recombination loss and improved conductivity of the ZnO interlayer are beneficial to acquire a higher short-circuit current density of 17.78 mA/cm2 and fill factor of 74.47%,...

A high performance photovoltaic ultraviolet photodetector (UVPD) based on Polyvinyl carbazole (PVK)/TiO2 heterojunction with CuInS2/ZnS quantum dots (CIS-Z QDs) doped in PVK layer was fabricated in a simple method with great exhibition of high responsivity (R) and fast response. When the device is in dark, the depleted p-n heterojunction structure will lead to a low dark current density with the value of 0.05 μA/cm2. Because of the different absorbance that the materials have, the detector has a narrow detection wavelength region from 310 nm to 350 nm. Meanwhile, due to the quantum size effect that CIS-Z QDs have, the electric-field intensity of the depletion is enhanced. Besides, the conductivity of the device has also been improved by CIS-Z QDs. Therefore, the photo-generated carrier will be effectively separated and lead to a high R and fast response with the value of 0.19 A/W and 24 m s. The research suggests that after doping CIS-Z QDs, organic/inorganic p-n hybrid heterojunction UVPDs possess the potential to enhance photo detection performance.

It is necessary to carefully adjust the interface characteristics between the interlayer and active layer in order to facilitate charge extraction and transfer. Here, a post-annealing treatment on the completed device with a Ag electrode is used to optimize the interface contact characteristics between WO3 and the active layer due to the inter-diffusion of the WO3 hole-extraction interface. The strengthened interface contact between them can improve the charge extraction and transfer across the active layer/WO3 interface. Furthermore, a thinner WO3 interlayer (75 A) is shown to qualify as an anode interlayer with excellent charge selection, extraction and transport capacities after the post-annealing treatment, which is beneficial for reducing the resistance loss introduced by the too thick WO3 layer and enhancing device performance. As a result, the device with the 75 A WO3 layer and 60 °C post-annealing treatment provides a higher fill factor of 74.5% and an optimal device performance of 9.66%. This work reveals a simple and universal method to modulate the interface contact characteristics between an evaporated transition metal oxide interlayer and an active layer, thus improving the device performance.

Applications of ZnO in photodetectors are limited by the great quantity of extrinsic majority carriers due to structural defects and difficult exciton dissociation due to the large exciton binding energy; these generally lead to a higher dark current (Id) and lower light current (Il), severely degrading the responsivity and detectivity. C dots are incorporated into an annealing-free ZnO layer to innovatively construct a local built-in electric field (Ebi) using the difference in the work functions; this simultaneously overcomes the drawbacks of the pristine ZnO photosensitive layer. In dark, the extrinsic majority carrier of ZnO is depleted around the incorporated C dots due to the self-depleting effect; thus, the Id decreases. Under UV illumination, the photogenerated exciton driven by the local Ebi is easily dissociated into a free charge carrier, contributing to the improved Il. This study paves a universal way to effectively improve the detection characteristics of photoconductive devices by incorporating the local Ebi.

Compared with the charge recombination loss from the unfavorable defects of the perovskite layer, the inferior charge transport characteristics of the interlayers deteriorate the efficiency in solar cells and slow the response speed in photodetectors. Here, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) is incorporated into a 4,4′,4′′-tris(3-methylphenylphenylamino)triphenylamine (m-MTDATA) layer to facilitate hole transport by providing deep electron traps. The increased work function and enlarged hole mobility of the composite hole transport layer are beneficial for the photoelectric conversion process of the perovskite photovoltaic devices. Consequently, an enhanced efficiency of 18.35% is achieved for the perovskite solar cells and a shortened decay time of 39.8 ns is obtained for the perovskite photodetectors. This work reveals the limitation of the transport layers on the perovskite solar cells and photodetectors, and provides an effective method to obtain high efficiency solar cells and fast photodetectors.

Rare earth elements (REEs) have been widely used to infer the provenance of sediments. However, sedimentary sorting and chemical weathering may produce REE compositions within sediments that vary with grain size, leading to complications and uncertainty when tracing possible source areas. In desert areas, the extent to which REE compositions within eolian sands are affected by sedimentary sorting along with which REE proxies can be used to indicate provenance requires further study. During our work, 73 samples were collected from the Badain Jaran Desert (BJD) and some nearby regions. These were analyzed for trace elements and REEs. Our results showed that the REE composition of these eolian sands varied considerably among the various grain-size fractions. We conclude that the REE composition of these eolian sands in the BJD is a function of sedimentary sorting and provenance rather than of chemical weathering. Among the REE proxies considered, variations in (La/Yb)N and Y/REE values seem mainly to have been affected by sedimentary sorting, whilst δCe, (La/Sm)N, (La/Gd)N, Y/Tb, Y/Er, and Ce/Nd ratios appeared primarily to have been governed by provenance. Therefore, we can infer that care is needed when using (La/Yb)N and Y/REE as proxies for determining eolian sand provenance; however, δCe, (La/Sm)N, (La/Gd)N, Y/Tb, Y/Er, and Ce/Nd ratios offer a more reliable perspective. Moreover, by using (La/Sm)N and (La/Gd)N as provenance proxies, we determined that hinterland lacustrine sediments are an important source of

In this paper, a powerful photoconductive interfacial layer was achieved by employing Cd2SSe/ZnS quantum dots (CSSQDs) to modify the electron-transport layers (ETLs) in polymer solar cells (PSCs). With the optimal concentration of CSSQDs and superior film process condition, the power conversion efficiency (PCE) was increased from 4.12% to 6.49% for P3HT:ICBA based device, leading to a tremendous1.6-fold performance enhancement. Moreover, the interlayer of CSSQDs could effectively improve the light absorption, the electron transport and extraction, as well as the better interfacial contact between the ETLs and active layers, accordingly resulting in a higher short-circuit current density, fill factor, and a lower series resistance, respectively. Hence, the introduction of CSSQDs interfacial layer could obtain a remarkably increased performance for the inverted PSCs.

To overcome drawbacks of the electron transport layer, such as complex surface defects and unmatched energy levels, we successfully employed a smart semiconductor–metal interfacial nanojunciton in organic solar cells by evaporating an ultrathin Al interlayer onto annealing-free ZnO electron transport layer, resulting in a high fill factor of 73.68% and power conversion efficiency of 9.81%. The construction of ZnO-Al nanojunction could effectively fill the surface defects of ZnO and reduce its work function because of the electron transfer from Al to ZnO by Fermi level equilibrium. The filling of surface defects decreased the interfacial carrier recombination in midgap trap states. The reduced surface work function of ZnO-Al remodulated the interfacial characteristics between ZnO and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM), decreasing or even eliminating the interfacial barrier against the electron transport, which is beneficial to improve the electron extraction capacity. The filled surface de...

Gastric cancer (GC) is the third leading cause of cancer-related mortality worldwide. Oxysterol-binding protein-related protein 8 (ORP8) functions as a sterol sensor that regulates a number of cellular functions. We showed that ORP8 expression was significantly lower in GC tissues and cells. Overexpression of ORP8 significantly inhibited GC cell proliferation in several GC cells. The formation of colonies in AGS cells was inhibited by the overexpression of ORP8. Moreover, overexpression of ORP8 significantly decreased implanted tumor growth in nude mice. Overexpression of ORP8 resulted in a significant increase in CHOP and GRP78 expression and the phosphorylation of PERK, indicating the occurrence of ER stress. Inhibition of ER stress by 4-PBA notably suppressed overexpression of ORP8-induced decrease of GC cell proliferation, formation of colonies, and implanted tumor growth. Overexpression of ORP8 resulted in a significant decrease in Wnt3a and β-catenin expression, and activation of Wnt signaling by HLY78 markedly blocked overexpression of ORP8-induced decrease in GC cell proliferation, formation of colonies, and implanted tumor growth. 4-PBA inhibited overexpression of ORP8-induced decrease in Wnt signaling. Furthermore, overexpression of ORP8 resulted in significant activation of mitochondrial apoptotic events and increase in apoptosis, which was inhibited by 4-PBA and HLY78. Induction of ER stress, inhibition of Wnt signaling, and apoptotic cell death were involved in ORP8-induced inhibition of GC cell proliferation. These findings indicate that downregulation of ORP8 plays a pivotal role in the progression of GC, and it may be a novel therapeutic target in the treatment of GC.

Cisplatin resistance has long been a major problem that restricts its use. A novel paradigm in tumor biology suggests that gastric tumor chemo-resistance is driven by gastric cancer stem cell-like (GCSCs). Growing evidence has indicated that microRNAs (miRNAs) contributes to chemo-resistance in gastric cancer (GC). Here, Lgr5+ cells derived from gastric cancer cell lines displayed stem cell-like features. Flow cytometry demonstrated the presence of a variable fraction of Lgr5 in 19 out of 20 GC specimens. By comparing the miRNA expression profiles of Lgr5+ GCSCs and Lrg5- cells, we established the upregulation of miR-132 in Lgr5+ GCSCs. The enhanced miR-132 expression correlated chemo-resistance in GC patients. Kaplan-Meier survival curve showed that patients with low miR-132 expression survived obviously longer. Functional assays results indicated that miR-132 promoted cisplatin resistance in Lgr5+ GCSCs in vitro and in vivo. Further dual-luciferase reporter gene assays revealed that SIRT1 was the direct target of miR-132. The expression of miR-132 was inversely correlated with SIRT1 in gastric cancer specimens. Furthermore, through PCR array we discovered ABCG2 was one of the downstream targets of SIRT1. Overexpression of SIRT1 down-regulated ABCG2 expression by promoting the de-acetylation of the transcription factor CREB. CREB was further activated ABCG2 via binding to the promoter of ABCG2 to induce transcription. Thus, we concluded that miR-132 regulated SIRT1/CREB/ABCG2 signaling pathway contributing to the cisplatin resistance and might serve as a novel therapeutic target against gastric cancer.

Organic-inorganic lead halide quasi-two-dimensional (2D) perovskites are promising gain media for lasing applications because of their low cost, tunable colour, excellent stability and solution processability

TiO

A smart interface modification strategy was employed to simultaneously improve short-circuit current density (Jsc) and open-circuit voltage (Voc) by incorporating a poly[(9,9-bis(3′-(N,N-dimethylamion)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctyl)-fluorene] (PFN) interlayer between a TiO2 film and an active layer, arising from the fact that PFN effectively eliminated the interface barrier between TiO2 and the fullerene acceptor. The work function (WF) of TiO2 was apparently reduced, which facilitated effective electron transfer from the active layer to the TiO2 electron transport layer (ETL) and suppressed charge carrier recombination between contact interfaces. Electron injection devices with and without a PFN interlayer were fabricated to prove the eliminated electron barrier, meanwhile photoluminescence (PL) and time-resolved transient photoluminescence (TRTPL) were measured to probe much easier electron transfer from [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) acceptor to TiO2 ETL, contributing t...

A heterojunction photo-conductive ultraviolet (UV) detector was developed based on TiO2 nanowires array (NWA) surrounded by N,N'-bis-(1-naphthalenyl)-N,N'-bis-phenyl-(1,1'-biphenyl)-4,4'-diamine (NPB). The novel and effective two-step method of static infusion and dynamic solution-cleaning was employed to fill NPB into TiO2 NWA gaps and simultaneously remove the unwelcomed top NPB layer. The device fabricated via the two-step method exhibited optimal performance compared to TiO2/NPB device with top NPB layer and TiO2 NWA device. In dark conditions, the TiO2/NPB heterojunction device without top NPB was found to possess the capacity of depleting majority carriers, thereby providing improved dark-resistivity to limit the dark current (Id). Under UV illumination, the depleting effect could be eliminated by the dissociation and accumulation of photo-generated carriers between pn heterojunction, leading to increased carrier density and photo-conductivity. It cleared up the high barrier due to the removal of top NPB layer, which was beneficial for hot electron transport than the device with top NPB layer under illumination, thereby achieving an enhanced light current (Il) to Id ratio of 1.67 × 104. A simple technology is provided to prepare organic-inorganic hybrid one-dimensional array heterostructure, which plays a remarkable role in the working of the UV detector, enhancing photo-conductivity and dark-resistivity of the device.

The preparation of well-defined silver (Ag) nanoparticle arrays is reported in this paper. Ag nanoparticles are electrodeposited on Indium tin oxide (ITO) coated glass substrates at 30 °C. The size, shape and periodicity of the Ag nanoparticle arrays are well-controlled. We study the effect of particle size and interparticle distance on reflection enhancement. The sample at the deposition potential of −0.2 V for an electrodeposition time of 3600 s exhibits an enhancement of 28% in weighted reflection in contrast with bare ITO glass. This study reports the high reflection of Ag nanoparticle arrays by electrodeposition method might be application to large-scale photovoltaic devices.

A remarkable performance ultraviolet (UV) photodetector was demonstrated by introducing a poly(9,9-dihexylfluorene) (PDHF) interlayer with the roles of barrier-blocking electron transport and light-inducing hole injection, leading to enhanced properties of the device both in dark and under UV illumination. The PDHF interlayer can efficiently block the electrons, which provides low dark current as well as the reduced noise for devices. Furthermore, the accumulation of photogenerated electrons causes the energy-band bending, leading to promoted gain of holes under UV illumination. The specific detectivity of the device with the PDHF interlayer reaches 1.86 × 1013 cm Hz1/2 W–1. Moreover, the response and recovery speed have been upgraded due to the improvement of the carrier transport mechanism.

In this paper, we present a facile method for the preparation of silver nanoparticles on aluminum-doped zinc oxide (AZO) via electrodeposition techniques at room temperature. The morphology and structure of silver nanoparticles are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), respectively. Due to localized surface plasmon resonances, as-prepared silver nanoparticles on AZO glass exhibited different reflectivity in contrast with bare AZO glass. The weighted reflection of AZO substrate increased from 10.2% to 12.8%. The high reflection property of silver nanoparticle arrays on AZO substrate might be applicable for thin film solar cells and other optoelectronics applications.

A novel MgZnO/ZnS heterojunction-based ultraviolet (UV) photodetector (PD) with high performance is fabricated by a facile sol-gel process and a successive ionic layer adsorption and reaction (SILAR) method. ZnS is coated onto the MgZnO film as an interface modification layer, which overcomes the drawbacks of the pristine MgZnO photosensitive layer, such as lower carrier mobility and more traps in the material, and greatly enhances UV-light absorption. The type-II heterostructure constructed by work function differences near the interface facilitate the separation of photogenerated carriers. Compared with the MgZnO PD, the optimized heterojunction PD (MgZnO/ZnS-10) yields a dramatically decreased dark current (≈1 nA), a remarkable responsivity (900 A/W) and an ultrahigh photo-to-dark current ratio (up to 2.3 × 105) under 325 nm light illumination at 5 V bias. These results provide a cost-efficient means for improving the properties of MgZnO PDs, and show the advantages of MgZnO/ZnS heterojunction PDs in UV detection. This study demonstrates that rational construction of novel heterojunctions holds great potential for fabricating high-performance photodetectors.

Heterostructured SrTiO 3 /TiO 2 nanocomposites have been fabricated by two steps in situ hydrothermal method with high photoelectric performance. Especially, TiO 2 plays the role of the resultant in first step reaction and the reactant in second synthesis. After the second hydrothermal method, apart from SrTiO 3 particles assembling on the surface of TiO 2 , we observe a web-linked composite of SrTiO 3 connecting TiO 2 nanowires above the middle of them and making up the void space. Consequently, a higher photoelectric performance is evaluated by the photo-to-dark current ratio which reaches to three orders of magnitude. The results presented here can be owing to the improvement of charge separation derived from the coupling effect of TiO 2 and SrTiO 3 nanocomposites. These experiments demonstrate the potential prospects of heterostructure with smaller nanostructure size in fabricating high-response UV detectors.

Metal sulfide Zn1-xCdxS nanowires (NWs) covering the entire compositional range prepared by one step solvothermal method were used to fabricate gas sensors. This is the first time for ternary metal sulfide nanostructures to be used in the field of gas sensing. Surprisingly, the sensors based on Zn1-xCdxS nanowires were found to exhibit enhanced response to ethanol compared to those of binary CdS and ZnS NWs. Especially for the sensor based on the Zn1-xCdxS (x = 0.4) NWs, a large sensor response (s = 12.8) and a quick rise time (2 s) and recovery time (1 s) were observed at 206 °C toward 20 ppm ethanol, showing preferred selectivity. A dynamic equilibrium mechanism of oxygen molecules absorption process and carrier intensity change in the NWs was used to explain the higher response of Zn1-xCdxS. The reason for the much quicker response and recovery speed of the Zn1-xCdxS NWs than those of the binary ZnS NWs was also discussed. These results demonstrated that the growth of metal sulfide Zn1-xCdxS nanostructures can be utilized to develop gas sensors with high performance.

One-dimensional ZnO nanofibers were synthesized by the electrospinning method. Then, a high spectrum selectivity ultraviolet detector was fabricated based on poly(N-vinylcarbazole) (PVK) and ZnO hybrids. At 4 V reverse bias, the dark current of the detector was as low as 9.6 nA. The device showed a large photo-to-dark current ratio of more than two orders of magnitude. Under the irradiation of 330 nm UV light, a peak responsivity of 2.62 A/W was achieved. The high photoresponse was attributed to the efficient carrier separation and convenient charge transport between ZnO and PVK. In addition, the detector possessed a narrow full-width at half-maximum of $\sim 36$ nm.

The performance of a Schottky metal–semiconductor–metal (MSM) ultraviolet (UV) photodetector is limited by the insufficient gain and the uncontrollable noise current. A remarkable detectivity UV detector is demonstrated based on graphene oxide (GO) modified TiO2 with high gain and low noise. The GO layer completely prevents the flow of electrons forming a hole-only device thus decreasing the dark current and noise current. Furthermore, gain of the holes is promoted under UV illumination. Moreover, the GO layer efficiently extracts the holes therefore reducing the fall time. Under a bias of 6 V, the responsivity value reaches 826.8 A W−1 and the noise current is only 1.8 pA, thereby, our device provides a detectivity of 2.82 × 1013 cm Hz1/2 W−1 at 280 nm. The results offer an effective approach to enhance the performance of a UV detector.

In this work, novel bowl-like TiO2 submicron scale particles were prepared via a simple electrospray technique combined with high-temperature calcination. The morphologies of the particles are easily controlled by changing the TBT content (16 wt%, 23 wt%, 30 wt%, 37 wt%) in the precursor solutions. To improve the xylene sensing properties of the TiO2, appropriate Ni amounts (0, 2, 4, and 6 mol% doping) were doped into the bowl-like particles. Among them, the 2 mol% Ni doped TiO2 bowl-like particles show the lowest optimum working temperature and highest response while demonstrating a fast response (9 s) and recovery speed (1.2 s) to 100 ppm xylene gas.

TiO 2 nanowires array is synthesized on the FTO via hydrothermal method, which is modified with ZnO prepared by using the crystallization method. The fabricated ultraviolet detector based on TiO 2 /ZnO heterojunction possesses high photoelectric performance evaluated by the photo-to-dark current ratio, which has been demonstrated to reach 4 orders of magnitude. The separation of electron–hole pairs is facilitated by the built-in electric field in heterojunction, resulting in a large photocurrent as well as a high responsivity, which can attain 150 A/W. Compared with the pure TiO 2 device, The red shift in both absorption spectrum and photo response provides a potential application for the TiO 2 /ZnO device.

In this article, the heterostructure of ZnO particles on single-crystal CdS nanowires (ZnO@CdS) has been successfully synthesized via a facile two-step solvothermal process. The appealing application of the ZnO@CdS heterostructure as visible-light photodetector (PD) is presented. Photocurrent illuminated with light (shorter than 510 nm) to dark-current ratio of structurally-optimized ZnO@CdS nanomaterials based photon detector was enhanced significantly compared to the value of the pristine CdS nanowires based one. The corresponding mechanism for the phenomenon was discussed. Additionally, measurements of time resolved responses were conducted. The ZnO@CdS heterostructure based device kept a fast rise (5 ms) and decay (10 ms) speed to irradiation. This work demonstrates a promising application of ZnO@CdS heterostructure based visible-light detectors with high photocurrent/dark-current ratio, ultrafast time response and very good stability.

In this letter, TiO2 thin films were prepared via sol-gel method and metal/semiconductor/metal ultraviolet (UV) detectors with Pt Schottky contact were fabricated. At 5 V bias, the dark current of the device was only 80 pA. Diffusion theory was adopted to analyze the low dark current mechanism, which is consistent with the experimental results. The device shows a remarkably reduced decay time of 41.53 ms. The low dark current and improved time response performance may be attributed to the high effective Schottky barrier between Pt and TiO2 film. High responsivity of 34.5 A/W was achieved at 300 nm UV light and the ratio of photocurrent to dark current is about five orders of magnitude, which is much larger than that of other semiconductor photodetectors.

A novel dark self-depleting ultraviolet (UV) photodetector based on a TiO

A heterojunction photo-conductive ultraviolet (UV) detector was developed based on TiO