Photocurrent Increment Research Articles

Top‐Down Fabrication of N‐GQDs Modified SnO2 with Improved Photoelectric Characteristics

AbstractN‐graphene quantum dots (N‐GQDs) are prepared using graphite as a carbon source and ammonia as a nitrogen source by a top‐down approach, and further combined with SnO2 to obtain SnO2/N‐GQDs composites by a hydrothermal method. SnO2/N‐GQDs composites are analyzed by morphology and structure characterization, and the composites with different N‐GQDs content are further investigated by instantaneous photocurrent response (I‐t), electrochemical impedance (EIS), linear scanning voltammetry (LSV), and Mott‐Schottky curves (MS). SnO2/N‐GQDs composites exhibit an obvious increment in photocurrent and a decrement in interface charge transfer impedance. When the addition of N‐GQDs is 1.5wt.%, the I‐t value of SnO2/N‐GQDs reaches the optimum of 3.84 × 10−5 A cm−2, which is 2.3 times as large as that of SnO2. Meantime, the carrier density of SnO2/N‐GQDs reaches 2.67 × 1021cm−3, which is 1.5 times as high as that of SnO2. The improvement is attributed to the combination of SnO2 and N‐GQDs, which promotes more charge carriers to be generated and transported under UV irradiation.

Preparation of a polyaniline/ZnO-NPs composite for the visible-light-driven hydrogen generation

Compositions of ZnO nanoparticles and polyaniline, in the form of emeraldine salt, were manufactured as thin layers by using the spin-coating method. Then, the effect of polyaniline content on their photoelectrochemical characteristics was studied. Results indicate that all the samples are sensitive to light. Besides, with 0.30% of PANI, the composite sample demonstrates the highest photocurrent density; also, its photocurrent increment starts to increase at a voltage of ⁓ 1.23 V (vs. RHE), which is approximately in accordance with the theoretical potential of water electrolysis. Furthermore, since the rate of electron–hole recombination in this composite sample is the lowest, it possesses the highest photoelectrochemical efficiency. Main findings were analyzed with respect to UV–visible absorption and photoluminescence spectra as well as SEM micrographs of the samples and Raman spectral measurements. Besides, electrochemical impedance spectroscopy analysis was applied to both pure ZnO and the sample with the best response. Effects of drying temperature and layer thickness were also investigated.

All-solution-processed perovskite/gallium nitride particles hybrid visible-blind ultraviolet photodetectors

Last decades have witnessed the rapid development of ultraviolet (UV) photodetectors in diversity of applications. The III-nitride semiconductor and metal halide perovskite have both performed promising UV-sensing optoelectronic properties. However, they are still suffering from either the high temperature epitaxial-growth or low photocurrent generated in UV range. In this work, we demonstrate an innovative MAPbCl3/GaN particle hybrid device with all-solution-processed deposition methods. Comparing to the control MAPbCl3 photoconductors, the photo-sensing ability of the hybrid device with the optimal concentration of GaN particles is more than one order of magnitude enhanced, and report a responsivity of 86 mA W−1, a detectivity of 3.1 × 1011 Jones and a rise/fall time of 1.1/10.7 ms at 360 nm. The photocurrent increment could be attributed to the enhanced UV absorption of GaN particles and facilitated charge separation and photoconductive gain at MAPbCl3/GaN heterojunction. This work paves a pathway towards the large-scale low-cost UV photodetectors in versatile applications.

Layered Heterostructures Based on MoS2/MoSe2 Nanosheets Deposited on GaN Substrates for Photodetector Applications

Due to the advanced properties of layered 2D materials, their heterostructuring with conventional 3D semiconductors is one of the promising ways to design efficient and affordable optoelectronic devices. However, systematic studies on designing 2D/3D heterojunctions with a focus on enhancing the photodetection properties are sparse in the literature. In this report, we present systematic experimental and theoretical investigations on 2D MoS2/MoSe2 heterostructuring with modified GaN substrates for designing efficient photodetectors. We achieved a gradual increment in photocurrent by engineering MoS2 and MoSe2 as single/double heterojunctions on GaN substrates. Time-correlated single-photon counting (TCSPC) results infer significant improvement in the lifetimes of the photoexcited charge carriers for the optimized MoS2/MoSe2/e-GaN heterostructure-based photodetectors. Interestingly, photodetectors designed with double heterojunctions that maintain type-II band alignment (e-GaN/MoSe2/MoS2) exhibit the highest photoresponsivity of 82 A/W, specific detectivity of 1.79 ×1014 Jones, external quantum efficiency of 27,880%, and stability for over 6 months in a laboratory testing environment under the illumination of 365 nm. Density functional theory (DFT) simulations establish the superiority of double heterojunctions with staircase band alignment for efficient charge carrier transport. This study provides fundamental insights on optimizing the band alignment for desired photodetection concerning 2D/3D integration, which can be exploited for other hybrid integrated systems and applications.

Ultrasensitive self-powered heterojunction ultraviolet photodetector of p-GaN nanowires on Si by halide chemical vapour deposition

In this study, we report the fabrication of quasi-aligned p-GaN nanowires (NWs) on n-Si (1 1 1) substrate by halide chemical vapour deposition (HCVD) using MgCl2 precursor and followed by low-energy electron beam irradiation to activate the Mg acceptor doping in GaN NWs. We aimed to attain a comprehensive understanding of p-doping in GaN NWs growth, extensive characterizations and fabrication of UV photodetector (PDs) based on p-GaN NWs/n-Si heterojunction. To realize the efficient UV photodetectors, we measure the current–voltage (I–V) characteristics of heterojunction PDs under dark and illuminated conditions and the I–V curve demonstrates good rectifying behaviours with 0.2 V turn-on voltage. At zero bias, the heterojunction PDs show a reverse photocurrent of 1.27 × 10−6 A with a very low dark current of 2.35 × 10−9 A under 325 nm UV illumination. Besides, the significance of the self-powered operation of UV PDs and the charge transfer mechanism are discussed with the aid of the energy band diagram. The substantial photocurrent increment with varying applied potential leads to narrowing the photo potential in the interface. The excitonic bound states present in p-GaN NWs/n-Si heterojunction is further elucidated. As a result, the heterojunction PDs demonstrate the high responsivity, detectivity, and external quantum efficiency of 134 mA W−1, 3.73 × 1013 Jones, and 51% respectively, at 0.1 V low applied potential under the reverse bias condition. The proposed work provides an archetype for Mg doping in GaN NWs ensembles, which will help to facilitate the heterojunction with n-Si to unleash the potential of self-powered UV PDs.

On-chip light detection using integrated microdisk laser and photodetector bonded onto Si board

Characteristics of a compact III–V optocoupler heterogeneously integrated on a silicon substrate and formed by a 31 µm in diameter microdisk (MD) laser with a closely-spaced 50 µm × 200 µm waveguide photodetector are presented. Both optoelectronic devices were fabricated from the epitaxial heterostroctructures with InGaAs/GaAs quantum well-dot layers. The measured dark current density of the photodetector was as low as 2.1 µA cm−2. The maximum link efficiency determined as the ratio of the photodiode photocurrent increment to the increment of the microlaser bias current was 1%–1.4%. The developed heterogeneous integration of III–V devices to silicon boards by Au-Au thermocompression bonding is useful for avoiding the difficulties associated with III–V epitaxial growth on Si and facilitates integration of several devices with different active layers and waveguides. The application of MD lasers with their lateral light output is promising for simplifying requirements for optical loss at III–V/Si interface.

Unbranched Hybrid Conducting Redox Polymers for Intact Chloroplast-Based Photobioelectrocatalysis.

Photobioelectrocatalysis (PBEC) adopts the sophistication and sustainability of photosynthetic units to convert solar energy into electrical energy. However, the electrically insulating outer membranes of photosynthetic units hinder efficient extracellular electron transfer from photosynthetic redox centers to an electrode in photobioelectrocatalytic systems. Among the artificial redox-mediating approaches used to enhance electrochemical communication at this biohybrid interface, conducting redox polymers (CRPs) are characterized by high intrinsic electric conductivities for efficient charge transfer. A majority of these CRPs constitute peripheral redox pendants attached to a conducting backbone by a linker. The consequently branched CRPs necessitate maintaining synergistic interactions between the pendant, linker, and backbone for optimal mediator performance. Herein, an unbranched, metal-free CRP, polydihydroxy aniline (PDHA), which has its redox moiety embedded in the polymer mainchain, is used as an exogenous redox mediator and an immobilization matrix at the biohybrid interface. As a proof of concept, the relatively complex membrane system of spinach chloroplasts is used as the photobioelectrocatalyst of choice. A "mixed" deposition of chloroplasts and PDHA generated a 2.4-fold photocurrent density increment. An alternative "layered" PDHA-chloroplast deposition, which was used to control panchromatic light absorbance by the intensely colored PDHA competing with the photoactivity of chloroplasts, generated a 4.2-fold photocurrent density increment. The highest photocurrent density recorded with intact chloroplasts was achieved by the "layered" deposition when used in conjunction with the diffusible redox mediator 2,6-dichlorobenzoquinone (-48 ± 3 μA cm-2). Our study effectively expands the scope of germane CRPs in PBEC, emphasizing the significance of the rational selection of CRPs for electrically insulating photobioelectrocatalysts and of the holistic modulation of the CRP-mediated biohybrids for optimal performance.

An Unbranched, Hybrid Conductive-Redox Polymer for Interfacing Intact Chloroplasts and Electrode Surfaces during Photobioelectrocatalysis

Photobioelectrocatalysis (PBEC) adopts the sophistication of photosynthetic units, their abundant availability, easy processing and sustainability, to convert solar energy into electricity. Specifically, the use of chloroplasts as photobioelectrocatalysts is desirable due to their metabolic independence and photoprotection mechanisms. However, the protein-based outer membranes of chloroplasts impede efficient charge transfer onto electrode surfaces during PBEC. Typical bio-inspired redox polymers used to ameliorate this charge transfer are branched, and contain redox pendants peripherally attached to a backbone. Pendants extract, and propagate electrons via collision-based electron tunneling. Conversely, we investigate the ability of an unbranched hybrid conductive-redox polymer, polydihydroxy aniline (PDHA), which has its redox moiety embedded in a conductive backbone. The redox moiety of PDHA is a quinone derivative, with redox potentials higher than the quinone-based redox active sites of chloroplasts. The biohybrid chloroplast-PDHA electrode encapsulates chloroplasts in a conductive matrix of PDHA, improving charge transfer. Holistically, PDHA facilitates the immobilization of chloroplasts and mediate electron transfer between chloroplasts and electrode surfaces. Our results demonstrate that a 120 % photocurrent increment is obtained upon combining chloroplasts with PDHA. Sequentially layering chloroplasts and PDHA on electrode surfaces evinces a 260 % increment in photocurrent responses. We report the highest photocurrent recorded with chloroplasts during PBEC (-48±3 µA cm-2) by pairing chloroplast-PDHA electrodes with diffusible redox mediator, 2,6-dichlorobenzoquinone. The study shows that redox polymer designs for artificially mediating electron transfer from chloroplasts can extend to unbranched conductive polymers in PBEC systems. Figure 1

Morphology changes of In-doped ZnO nanosheets via ZnCl2 and InCl3 vapor formation during thermal dissipation annealing process and improved UV photoresponse properties

Ultraviolet (UV) photodetectors that are fabricated using ZnO thin films exhibit higher photocurrent stability, without a complex filter, than that exhibited by Si-based UV photodetectors. However, the ZnO-based UV photodetectors possess several drawbacks such as slow response speed, low on/off current ratio, and low sensitivity. These drawbacks can be overcome by regulating the number of free carriers and point defects that affect the photocurrent increment and the response speed of the UV photodetectors. In this study, indium (In)-doped ZnO (IZO) thin films were deposited via sol-gel spin coating. Subsequently, the amorphous IZO thin films were crystallized via thermal dissipation annealing (TDA). This facilitated the regulation of the number of point defects and free carriers, and the surface roughness of the IZO thin films decreased with the increase in the doping concentration. The UV photosensitivity of the IZO thin films was higher than that of the undoped ZnO thin films. The IZO thin films also exhibited the highest photoresponsivity and UV photoresponse speed. The technique that was devised in the study was concluded to be a feasible route for the fabrication of ZnO-based UV photodetectors with high photosensitivity, photoresponsivity, and UV photoresponse speed.

Novel Ag decorated, BiOCl surface doped AgVO3 nanobelt ternary composite with Z-scheme homojunction-heterojunction interface for high prolific photo switching, quantum efficiency and hole mediated photocatalysis

A ternary composite Ag@AgVO3/BiOCl possessing homojunction-heterojunction interface with varied BiOCl concentration was obtained through a facile hydrothermal route. Ag deposition in Ag@AgVO3 nano-belt was achieved through in-situ generation and deposition of Ag forming a homojunction. Whereas Ag@AgVO3/BiOCl heterojunction was constructed through the surface doping. This unique two-way interaction and the interface formation were revealed through the electron microscope and crystallographic analysis. The localized surface plasmon resonance of Ag and the efficient orbital mixing with BiOCl of 1:1 B/Ag@A compound has imparted a remarkable light harvesting and photo switching ability in the ternary composite material. Conductive nature of the Ag nanoparticle has promoted light absorption in the visible region and reduced the charge transfer resistance. Reduction of width in space charge region along with the increase in the amount of surface charge carrier has resulted in an outstanding increment in photocurrent. The solar photocatalysis evaluated against the aqueous phase removal of methyl orange and Bisphenol A showed 100 % and 51 % removal in 50 and 240 min, respectively. Studies were extended to understand the sensitization effect of dye. Theoretical modelling of band structure drawn from charge trapping experiments showed the prevalence of Z-scheme mechanism with holes mediated catalytic degradation. Improved charge harvest, separation and transmission has inserted a higher quantum efficiency in the material. BPA removal was enhanced to 82 % after the peroxide activation.

Research on photosensitive gate ferroelectric integrated GaN HEMT photodetector

In this paper, we take advantage of the high sensitivity of two-dimensional electron gas concentration in the heterojunction channel of a GaN high electron mobility transistor (HEMT) to device surface states and gate voltages. By integrating a HEMT with ferroelectric materials with photovoltaic effects, a photo-sensitive gate HEMT photodetector based on ferroelectric integration is obtained. By exploring the ferroelectric and composite film sputtering growth epitaxial atmosphere, a high-performance PZT/ZnO composite ferroelectric film grown in an oxygen-containing atmosphere is obtained. Comparing the PZT and LiNbO3 (LN) ferroelectric thin films prepared with or without the buffer layer, the following conclusions are obtained. The quantum efficiency of the PZT/ZnO film increases by 240% and 596% at the peak of 300–400 nm, reaching 14.55%; the residual polarization of the PZT film obtained in an oxygen-containing atmosphere reaches 52.31 μC/cm2; the PZT/ZnO composite film has better fatigue characteristics. The GaN HEMT detector prepared by using magnetron sputtered PZT/ZnO as the sensing gate under the oxygen atmosphere has a photocurrent increment of 11.51 mA under ultraviolet light and a responsivity of 111A/W at 365 nm. At the same time, the device has τr = 0.12 s and τf = 8.3 s transient response. The research in this paper shows that a new structure photodetector based on a GaN HEMT has excellent ultraviolet light response, which provides a new research direction for the light detection mechanism.

Black Phosphorus Quantum Dot-Sensitized TiO2 Nanotube Arrays with Enriched Oxygen Vacancies for Efficient Photoelectrochemical Water Splitting

Photon absorption, charge separation and transportation, and charge-induced reactions at the active sites are the main crucial factors involved in the photoelectrochemical (PEC) water splitting. Herein, a combination of black phosphorus quantum dot (BPQD) sensitization and defect engineering strategies is employed to optimize the PEC performance of one-dimensional TiO2 nanotube array (NTA) photoanodes. The as-prepared TiO2–x/BP electrode exhibits a strong photocurrent density under simulated solar light irradiation, which is almost ∼3 times higher than that of bare TiO2. Specifically, the photocurrent increment of TiO2–x/BP is even larger than the sum of TiO2–x and TiO2/BP, verifying the synergistic effect of oxygen vacancies and BPQD sensitization. The maximum photoconversion efficiency of TiO2–x/BP is as high as 0.35%, while the value of TiO2 NTAs is calculated to be 0.13%. The results reveal that oxygen vacancies and BPQDs in the TiO2–x/BP composite not only facilitate the charge separation and transportation but also enhance the activity and quantity of reactive sites for water oxidation. The present strategy might open new routes to develop high-performance photoelectrodes for water splitting.

Nano-hetero-structured thin films, ZnO/Ag-(α)Fe2O3, with n/n junction, as efficient photoanode for renewable hydrogen generation via photoelectrochemical water splitting

Significant gains in PEC water splitting photocurrent were recorded using n/n junction bi-layered nano-hetero-structured (BNHS) thin films, ZnO/Ag-(α)Fe2O3, as photoanode. Films, synthesized over ITO (In:SnO2) glass plates, were characterized by X-ray diffractometry, field emission-scanning electron microscopy, atomic force microscopy, UV–visible spectroscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. PEC cell, fabricated through electrical contacting of BNHS films (3% Ag incorporation)/electrolyte (0.1 M NaOH, pH 13, temperature 32 ± 3.6 °C) junction working electrode with platinum counter electrode and saturated calomel reference electrode, yielded nearly 2 and 20 fold increment in photocurrent, against monolayered pristine ZnO and (α)Fe2O3 thin films, respectively. Marked gain in PEC cell-response towards water splitting was attributed to high active surface area and n/n hetero-junction that favored the separation and transfer of photogenerated charge carriers.

Estimation of the potential for increasing the efficiency of GaInP/GaAs/Ge multi-junction solar cells by using quantum-size objects

A study of GaAs solar cells (SCs) with various quantum-sized objects has been carried out. In0.2Ga0.8As quantum wells, In0.4Ga0.6As quantum well-dots (QWDs), In0.8Ga0.2As and InAs quantum dots have been considered. The increment in photocurrent and the reduction of open-circuit voltage have been calculated using dark IV and spectral characteristics. An analytical model for estimating the efficiency of triple-junction SCs with quantum objects has been described. The calculations have shown that the optimized QWDs have a potential for increasing the efficiency of GaInP/GaAs/Ge SC from 29.8% to 30.8% (AM0, 1 sun) and from 41.6% to 43.1% (AM1.5D, 360 suns).

An effective strategy to promote hematite photoanode at low voltage bias via Zr4+/Al3+ codoping and CoOx OER co-catalyst

Herein, we report the surface treatment on Zr4+/Al3+ codoped α-Fe2O3 photoanode for high-performance photoelectrochemical water splitting. A high-temperature quenching exhibits the Zr4+/Al3+ codoping in α-Fe2O3 photoanode without damaging morphology. The presence of Zr4+/Al3+ codoping shows a cathodic shift in onset potential, but lack of increment in photocurrent reveals the major role of passivation and the minimum doping effect of aluminum. Additionally, CoOx cocatalyst exhibits increment in photocurrent with the greater cathodic shift in onset potential than the pristine α-Fe2O3 nanorods. The CoOx surface-reworked Zr4+/Al3+ codoped α-Fe2O3 photoanode displays the highest photocurrent of 1.5 mA/cm2 at 1.23 V vs. RHE (76% increment over the pristine α-Fe2O3) and 0.7 mA/cm2 at 1.0 V vs. RHE (102% increment over the pristine α-Fe2O3). The systematic characterization carried out using x-ray diffraction and scanning electron microscopy confirms that after Zr4+/Al3+ codoping, and surface treatment, the crystalline structure, and morphology of the photoanodes remains unchanged. X-ray photoelectron spectroscopy confirmed the existence of Zr4+/Al3+ codopants in the hematite nanostructure. The electrochemical properties of the photoanode suggest that Al3+ and Zr4+ codoping, as well as surface treatment with CoOx, cocatalyst lowers charge transfer resistance across the FTO/hematite interface, and hematite/electrolyte interface. This designs not only lowers onset potential but also offers the blueprint for the development of an efficient catalyst for solar water oxidation.

A self-powered photoelectrochemical biosensor for H2O2, and xanthine oxidase activity based on enhanced chemiluminescence resonance energy transfer through slow light effect in inverse opal TiO2

TiO2 inverse opal photonic crystals (IOPCs) were fabricated by using polystyrene template. TiO2 IOPCs based photoelectrochemical (PEC) biosensor was fabricated for the precise and stable detection of Heme without external irradiation. Then, the sensitization of TiO2 IOPCs was fulfilled with CdS quantum dots (QDs) by SILAR method to form ITO-TiO2 IOPCs–CdS:Mn electrode, which in turn was used to construct a PEC biosensor. The uniform porous structure of IOPCs with a large surface area is conducive to the excellent electronic transmission and QDs deposition. Also, the energy level matching between the conduction bands of CdS QDs and TiO2 IOPCs widened the range of light absorption, allowing for electron injection from excited CdS QDs to TiO2 upon luminol chemiluminescence, which enhanced the photocurrent. Furthermore, when the red edge of the photonic stop band of TiO2 IOPCs overlapped with the band gap of TiO2, and chemiluminescence emission of luminol, a substantial photocurrent increment was observed due in part to the slow light effect. The biosensor possesses a large linear detection range of 0.063–4 mM with a LOD of 19 μM for H2O2. Also, xanthine oxidase activity was determined with a linear measurement range of 0.01–15 mU/mL. Our strategy opens a new horizon to IOPCs based and QDs sensitized PEC sensing, which could be more sensitive, convenient and inexpensive for clinical and biological analysis. As far as we know, the largest photocurrent generation by luminol chemiluminescence was observed thanks to the use of semiconducting hybrid IOPCs material even at 0 V.

Dethermalization of carriers in GaAs solar cells with quantum objects

Temperature photovoltaic dependencies have been measured at 90–350 K for a single-junction GaAs-based p-i-n solar cell and for a similar solar cell with imbedded in i-region In0.4Ga0.6As quantum objects. A theoretical approach for analyzing temperature dependencies of open circuit voltage has been proposed. A dethermalization of quantum objects has been observed at temperatures below 170 K, and the temperature of full dethermalization is estimated to be 80 K. It has been shown that dethermalized quantum objects are not involved in the photovoltaic process and may cause photocurrent losses, while, when thermalized, quantum objects give a photocurrent increment. It has been found that the energy difference between optic transitions in GaAs and in quantum objects is independent on temperature. Analysis of the temperature dependencies has allowed for the estimation of effective band gap energy of quantum objects which, at room temperature, was found to be 1.2 eV.

Синтез нанонитей оксида индия-цинка и исследование их чувствительности к ультрафиолетовому излучению

Indium-zinc oxide (IZO) nanofibers are synthesized on Si-SiO2 substrates by the electrospinning method. The nanofibers’ dimensions, morphology, crystalline structure, and composition are studied by scanning electron microscopy, atomic force microscopy, energy dispersive X-ray analysis, and X-ray diffraction. The results of studying the electrical properties of nanofibers, as well as their sensitivity to UV radiation depending on the In to Zn concentration ratio, are presented. It is shown that the highest sensitivity to UV is observed at the indium content of about 50 atomic %. The photocurrent increment in this case, with respect to the dark current, is more than 4 orders of magnitude. The response and recovery times are 60 and 500 s, respectively. The results obtained suggest that IZO nanofibers can find application as UV sensors with improved characteristics.

A dual signal-on photoelectrochemical immunosensor for sensitively detecting target avian viruses based on AuNPs/g-C3N4 coupling with CdTe quantum dots and in situ enzymatic generation of electron donor

A sensitive and specific photoelectrochemical (PEC) immunosensor was fabricated for subgroup J avian leukosis viruses (ALV-J) analysis based on a dual signal-on strategy. Gold nanoparticles (AuNPs) decorated graphitic carbon nitride (AuNPs/g-C3N4) as photoelectrochemical species and primary antibody (Ab1) against ALV-J were immobilized onto ITO electrode in turn. An ALP-CdTe-Ab2 bio-conjugant was fabricated by assembling second antibody (Ab2) and alkaline phosphatase (ALP) to CdTe quantum dots (QDs) surface. The PEC immunosensor was fabricated by successively anchoring the target ALV-J and ALP-CdTe-Ab2 bio-conjugants onto electrode surface via the immune recognition. By virtue of the matched energy levels between CdTe QDs and AuNPs/g-C3N4, ALP-CdTe-Ab2 bio-conjugants could serve as the PEC active probes for photocurrent enhancement. Moreover, the photocurrent response could be further enhanced attributed to the ALP catalytic chemistry to in situ produce ascorbic acid for electron donating, achieving an effective dual signal-on mode for PEC assay. On the basis of the ALV-J titers-dependent photocurrent increment, the fabricated PEC immunosensor showed high sensitivity, specificity and stability for ALV-J assay in a wide linear range with a low detection limit of 85 TCID50/mL. This PEC immunosensor with the dual signal-on strategy may open up a promising platform for more target analytes in novel immune analysis and clinical diagnostics.

Effects of Zn2+ ion doping on hybrid perovskite crystallization and photovoltaic performance of solar cells

To achieve a reproducible perovskite film with full surface coverage, Zn2+ ions are introduced to partially replace Pb2+ ions in this work. Results indicate that the crystallization and formation of CH3NH3Pb1−xZnxI3 film with micrometer grain size could be changed by the micro-strain for lattice shrink. The bandgap and optical properties of perovskite films are improved due to trace amounts of Zn2+ ion dopant. More importantly, the solar cell device based on the Zn-doped perovskite film shows an increment in photocurrent of 21.13 mA cm−2 and power conversion efficiency (PCE) of 16.6%. Electrochemical impedance spectroscopy (EIS) measurements reflect that the charge recombination resistance and charge accumulation capacitance of devices based on MAPb0.98Zn0.02I3 film are lower than that of the control device. However, present results also implied that MAPb1−xZnxI3 films are still necessary to be extensively developed and optimized for further enhancing the device photovoltaic performance.