Maximum Photoresponsivity Research Articles

Comparative Analysis of Thin and Thick MoTe2 Photodetectors: Implications for Next-Generation Optoelectronics

Due to its outstanding optical and electronic properties, molybdenum ditelluride (MoTe2) has become a highly regarded material for next-generation optoelectronics. This study presents a comprehensive, comparative analysis of thin (8 nm) and thick (30 nm) MoTe2-based photodetectors to elucidate the impact of thickness on device performance. A few layers of MoTe2 were exfoliated on a silicon dioxide (SiO2) dielectric substrate, and electrical contacts were constructed via EBL and thermal evaporation. The thin MoTe2-based device presented a maximum photoresponsivity of 1.2 A/W and detectivity of 4.32 × 108 Jones, compared to 1.0 A/W and 3.6 × 108 Jones for the thick MoTe2 device at 520 nm. Moreover, at 1064 nm, the thick MoTe2 device outperformed the thin device with a responsivity of 8.8 A/W and specific detectivity of 3.19 × 109 Jones. Both devices demonstrated n-type behavior, with linear output curves representing decent ohmic contact amongst the MoTe2 and Au/Cr electrodes. The enhanced performance of the thin MoTe2 device at 520 nm is attributed to improved carrier dynamics resulting from effective electric field penetration. In comparison, the superior performance of the thick device at 1064 nm is due to sufficient absorption in the near-infrared range. These findings highlight the importance of thickness control in designing high-performance MoTe2-based photodetectors and position MoTe2 as a highly suitable material for next-generation optoelectronics.

One-Dimensional ZnO Nanorod Array Grown on Ag Nanowire Mesh/ZnO Composite Seed Layer for H2 Gas Sensing and UV Detection Applications.

Photodetectors and gas sensors are vital in modern technology, spanning from environmental monitoring to biomedical diagnostics. This paper explores the UV detection and gas sensing properties of a zinc oxide (ZnO) nanorod array (ZNA) grown on silver nanowire mesh (AgNM) using a hydrothermal method. We examined the impact of different zinc acetate precursor concentrations on their properties. Results show the AgNM forms a network with high transparency (79%) and low sheet resistance (7.23 Ω/□). A sol-gel ZnO thin film was coated on this mesh, providing a seed layer with a hexagonal wurtzite structure. Increasing the precursor concentration alters the diameter, length, and area density of ZNAs, affecting their performance. The ZNA-AgNM-based photodetector shows enhanced dark current and photocurrent with increasing precursor concentration, achieving a maximum photoresponsivity of 114 A/W at 374 nm and a detectivity of 6.37 × 1014 Jones at 0.05 M zinc acetate. For gas sensing, the resistance of ZNA-AgNM-based sensors decreases with temperature, with the best hydrogen response (2.71) at 300 °C and 0.04 M precursor concentration. These findings highlight the potential of ZNA-AgNM for high-performance UV photodetectors and hydrogen gas sensors, offering an alternative way for the development of future sensing devices with enhanced performance and functionality.

Centimeter-scale single-crystal hexagonal boron nitride freestanding thick films as high-performance VUV photodetectors

Large-scale hexagonal boron nitride (h-BN) single crystals are highly desirable not only as the substrate or dielectric for van der Waals heterostructures, but also the promising candidates in optoelectronics, electronics, detectors, as well as recently boomed room-temperature single-photon sources. Here, we report the synthesis of centimeter-scale single-crystal h-BN films with hundreds of micrometer thickness via the metal flux method. The growth control along the out-of-plane and in-plane directions of h-BN crystals is realized by the adjustment of NiCr alloy composition, from which the limited solubility of N atoms can be promoted by high diffusion in molten reactants. This also benefits to forming a distinct interface between the synthesized h-BN crystals and the metal ingot, giving rise to an easy exfoliation of the large area high-quality thick films. Such h-BN crystals have been demonstrated as both self-powered flexible and rigid vacuum-ultraviolet photodetectors, allowing for efficient photodetection in terms of high responsivity, rapid response speed, and high operational temperature. A maximum photoresponsivity of 3.35 mA/W is achieved at a wavelength of 185 nm with an operational temperature spanning to 500 °C (and possibly beyond). The large-area freestanding h-BN single crystal described herein reveals great potential as a high-performance photodetector, and versatile platform for other superb electronic and optoelectronic devices.

Liquid phase exfoliation of few-layer borophene with high hole mobility for low-power electronic devices

Borophene, the two-dimensional allotrope of boron, has garnered significant interest in recent years due to its exceptional electronic, mechanical, and optical properties. In this work, an environment-friendly green approach has been utilized to synthesize p-type borophene, which consists of few layers as evidenced by electron and atomic force microscopic images. The Raman analysis indicated that these borophene layers possess β12 and χ3 phases. The photoemission spectra of these samples exhibit single exponential decay with a long lifetime of 7.2 µsec, showcasing its potential as a phosphorescent material in optoelectronics and quantum technologies. The photo-sensing capability of borophene was investigated by fabricating a Si/SiO2/Borophene/Ti/Pt photo-detector, which achieved an external quantum efficiency of 31 %, maximum photo responsivity of 200 mAW−1 and detectivity of 8.7x1011 Jones. Hall effect van der Pauw measurements revealed the p-type conductivity of the borophene film, along with a high hole mobility of 931.44 cm2V-1s−1 and a charge carrier density of 2 x 1012 cm−3, rendering these layers suitable for high-speed and low power electronic devices. This work emphasizes the importance of novel 2D materials like borophene with exceptional optoelectronic characteristics for developing future low-power electronic devices with remarkable performance.

Staggered band alignment of n-Er2O3/p-Si heterostructure for the fabrication of a high-performance broadband photodetector

The low responsivity of conventional Silicon photodiodes in ultraviolet and near-infrared regimes restricts their utility as broadband photodetectors (BBPDs). Despite ongoing investigations into various p-n heterostructures for Silicon-based BBPDs, challenges such as high dark current (Idark), low collection efficiency, low detectivity, and compatibility issues with large-scale Silicon-based devices persist. In this context, we have fabricated relatively unexplored n-Er2O3/p-Si heterojunction-based BBPDs. Polycrystalline Er2O3 thin films (∼110 nm) were deposited on p-Si 〈100〉 substrates by radio frequency magnetron sputtering. Although this process induces a microstrain of approximately 0.022 and a dislocation density of about 0.00303/nm2, the presence of optically active defects is minimal, indicated by a low Urbach energy (∼0.35 eV). X-ray photoelectron spectroscopy (XPS) analysis confirms staggered band alignment at the heterointerface, facilitating efficient charge carrier separation and transport. Consequently, the In/p-Si/n-Er2O3/In device demonstrated significant BBPD properties– low Idark ∼0.15 μA (at +5 V), photo-to-dark current ratio (PDCR) ∼6.5 (at +5 V, 700 nm) with a maximum photoresponsivity ∼22.3 A W−1, and impressive detectivity (∼1013 Jones) even in UV-C region where traditional silicon-based photodetectors respond feebly. The device also demonstrates transient photo-response across an ultrawide spectrum (254 nm–1200 nm) with a fast rise time/fall time ∼79 ms/∼86 ms (at −5 V for 600 nm illumination). This work establishes a straightforward and reliable method for proper material engineering, surface texturing, staggered heterojunction formation, and high-performance BBPD fabrication with prominent broad-spectrum responsivity, sizeable detectivity, and fast response. The integration of these BBPDs with Silicon opens possibilities for their use in electronic devices containing optical switches for communications and broadband image sensors, enhancing their utility in various applications.

Enhancement of pH imaging of light addressable potentiometric sensor by colloidal spherical lens array

Visualizing the distribution of pH in a solution is an important basis for monitoring reaction processes and metabolic changes in micro-biochemical species. Light addressable potentiometric sensor (LAPS), as a simple structure, flexible imaging, low-cost and label-free electrochemical sensor, has been widely used to pH imaging. However, its spatiotemporal resolution is greatly affected by the frequency of modulation light, thus limiting its imaging performance. In this study, LAPS device modified by well-ordered and low-cost polystyrene (PS) colloidal monolayer as spherical lens array is proposed to obtain higher available modulation frequency of the maximum photoresponse. The morphology, optical properties and the electric field distribution of PS colloidal spherical lens array were tested and analyzed. pH sensing, imaging of uniform pH solution, the spatiotemporal pH imaging and dynamic imaging of enzymatic reactions of LAPS modified by PS colloidal spherical lens array were tested and evaluated. The experimental results show that LAPS modified by PS colloidal spherical lens array not only has acceptable pH sensing, but also widens the modulation frequency of the maximum photoresponse to 40 kHz. LAPS modified by colloidal spherical lens array modulated at the frequency of 40 kHz shows acceptable sensitivity and linearity, good reproducibility and stability, high SNR and high-spatiotemporal pH imaging capability. This work can be suitable for high-spatiotemporal monitoring of the changes in electrolyte environmental pH caused by the reaction and metabolism of the biochemical species.

Development of Sub‐Band in Spray‐Deposited Cr‐Substituted Chalcopyrite Thin Films for Advancing Solar Cell Efficiency

Designing effective strategies for mitigating energy crisis highlights a research gap in current solar cell technologies. This study explores the inherent physicochemical properties of thin films composed of copper gallium sulfide telluride (CuGa1−xCrx(S,Te)2) with chromium substitution, prepared through the chemical spray pyrolysis technique. The investigation showcases how the concept of intermediate band structuring contributes to enhancing solar cell efficiency. This enhancement can be attributed to the remarkable mobility (from 1.80 to 5.48 cm2 V−1 s−1) and conductivity (from 1.00 to 6.06 S cm−1) exhibited by pure and 0.1 chromium thin films, respectively. Notably, the Cr‐0.1‐substituted CGST film displays maximum photoresponsivity of 0.624 AW−1, an external quantum efficiency of 145%, and a detectivity of 2.37E10. The fabricated solar cell is subjected to theoretical simulation using solar cell capacitance simulator‐1D software, revealing an upward trend in efficiency from 7.13% to 11.23% with increasing Cr substitution from 0.025 to 0.1. This efficiency improvement can be ascribed to the reduction in bandgap (from 2.40 to 1.72 eV) and the creation of a sub‐band in CGST due to Cr incorporation, as substantiated by UV–vis and NIR spectroscopy. These outcomes suggest that Cr‐0.1‐substituted CGST holds promise as a potential thin film absorber material in solar photovoltaics.

Ultrahigh Photosensitivity Based on Single-Step Lay-on Integration of Freestanding Two-Dimensional Transition-Metal Dichalcogenide.

Two-dimensional transition-metal dichalcogenides have attracted significant attention because of their unique intrinsic properties, such as high transparency, good flexibility, atomically thin structure, and predictable electron transport. However, the current state of device performance in monolayer transition-metal dichalcogenide-based optoelectronics is far from commercialization, because of its substantial strain on the heterogeneous planar substrate and its robust metal deposition, which causes crystalline damage. In this study, we show that strain-relaxed and undamaged monolayer WSe2 can improve a device performance significantly. We propose here an original point-cell-type photodetector. The device consists in a monolayer of an absorbing TMD (i.e., WSe2) simply deposited on a structured electrode, i.e., core-shell silicon-gold nanopillars. The maximum photoresponsivity of the device is found to be 23.16 A/W, which is a significantly high value for monolayer WSe2-based photodetectors. Such point-cell photodetectors can resolve the critical issues of 2D materials, leading to tremendous improvements in device performance.

Nanometer-Resolved Operando Photo-Response of Faceted BiVO4 Semiconductor Nanoparticles.

Photo(electro)catalysis with semiconducting nanoparticles (NPs) is an attractive approach to convert abundant but intermittent renewable electricity into stable chemical fuels. However, our understanding of the microscopic processes governing the performance of the materials has been hampered by the lack of operando characterization techniques with sufficient lateral resolution. Here, we demonstrate that the local surface potentials of NPs of bismuth vanadate (BiVO4) and their response to illumination differ between adjacent facets and depend strongly on the pH of the ambient electrolyte. The isoelectric points of the dominant {010} basal plane and the adjacent {110} side facets differ by 1.5 pH units. Upon illumination, both facets accumulate positive charges and display a maximum surface photoresponse of +55 mV, much stronger than reported in the literature for the surface photo voltage of BiVO4 NPs in air. High resolution images reveal the presence of numerous surface defects ranging from vacancies of a few atoms, to single unit cell steps, to microfacets of variable orientation and degree of disorder. These defects typically carry a highly localized negative surface charge density and display an opposite photoresponse compared to the adjacent facets. Strategies to model and optimize the performance of photocatalyst NPs, therefore, require an understanding of the distribution of surface defects, including the interaction with ambient electrolyte.

Photogating enhanced photodetectors dominated by rubrene nanodots modified SnS2 films

The hybrid-induced photogating effect is considered as an effective way for photoconductance modulating in low-dimensional photodetectors. Besides, through constructing the local photogate vertical heterostructures on two-dimensional SnS2 surface can significantly increase its photoconductive gain. However, the potential of this photogain mechanism for SnS2 films has not yet been revealed in practical photodetection devices. To investigate its special advantages on promoting the optical-sensing activity, the high-quality SnS2 films with discrete, micro-area, and uniform rubrene-nanodots modification have been prepared. Benefit from the local interfacial photogating effect induced by hole trap states by rubrene-nanodots, the light-absorption and carrier-excitation efficiencies were significantly enhanced. Afterwards, the high-performance photodetector was designed based on the photogate vertical heterostructures of rubrene-nanodots/SnS2, which demonstrated an enhanced photoelectric response to 1064 nm light. Note that the maximum photocurrent density, photoresponsivity, and photodetectivity can reach up to 0.389 mA cm−2, 388.71 mA W−1, and 1.13 × 1010 Jones, respectively. Importantly, the optimal band-structure offsets accelerated the localized hole transfer from SnS2 film to rubrene-nanodots. The trapped holes in rubrene-nanodots induced an enhanced interface gating effect, which may help to modulate the number and lifetime of excess electrons under light illuminations. These superior features make the newly-developed photodetector be suitable for future multifunctional photodetection applications.

Synergistic exploration of dye degradation and pulse photoresponse using MoS2 nanosheets: Towards sustainable remediation and optoelectronic advancements

Two essential areas of research with important implications for environmental cleanup and optoelectronic device applications are dye degradation and the comprehension of the pulse photo-response of transition metal dichalcogenide (TMDC) materials. Using MoS2 Nanosheets, this study evaluates the pulse photo-response characteristics of dyes and their degradation mechanisms. The article focuses into the effectiveness of MoS2 materials in dye removal as well as their function in photocatalytic degradation processes. Additionally, the MoS2 nanosheets are easy to utilise in solutions containing methylene blue (MB) and can be used as a high-performance recyclable photocatalyst to photodegrade organic dyes like methylene blue (MB) in around 120 min when exposed to light. The pulse photoresponse behaviour of MoS2 Nanosheets (NSs) is also investigated, with an emphasis on their distinct charge carrier dynamics and potential uses in ultrafast photodetectors. The working electrodes constructed from MoS2 nanosheets demonstrate an obvious photovoltaic effect with a photocurrent of 6.920 A/cm2 at zero bias and 100 mW/cm2 of polychromatic light. Due to optimal conditions, the maximum photoresponsivity of 5.669 mA/W and Detectivity of 7.708 × 108 Jones is achieved. The intention is to provide details on the way dye degradation and pulse photo-response interact synergistically in MoS2 nanosheets and highlight their potential for improved optoelectronic devices and environmentally friendly remediation.

Highly stable and sensitive photoelectrochemical photodetectors based on a ZnO nanorod/monolayer MoS2 nanosheets heterostructure

Construction of type-II heterostructures between metal oxide nanorod arrays and narrow band gap semiconductors is a proven strategy for enlarging the surface area, shortening the diffusion length, broadening the light harvesting ability, and facilitating carrier transport, which are of great significance for photoelectrochemical (PEC) photodetectors. A ZnO/MoS2 heterostructure was designed and fabricated via a facile hydrothermal process accompanied by chemical vapor deposition method. The ZnO nanorod/monolayer MoS2 nanosheet heterostructure was revealed with scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. These heterojunction-based PEC photodetectors showed higher photoresponsivity (4.2 mA/W) than those of ZnO (∼0.9 mA/W) and MoS2 photodetectors (∼0.007 mA/W) due to its fast interfacial charge transfer and efficient light capture. Furthermore, the ZnO/MoS2 heterostructural photodetectors exhibited a maximum photoresponsivity of approximately 5.0 mA/W at 420 nm and long-term stability even over 6 h. Our work paves the way to rationally designed heterostructures for high-performance and stable photodetectors and beyond.

Near-Field Photodetection in Direction Tunable Surface Plasmon Polaritons Waveguides Embedded with Graphene.

2D materials have manifested themselves as key components toward compact integrated circuits. Because of their capability to circumvent the diffraction limit, light manipulation using surface plasmon polaritons (SPPs) is highly-valued. In this study, plasmonic photodetection using graphene as a 2D material is investigated. Non-scattering near-field detection of SPPs is implemented via monolayer graphene stacked under an SPP waveguide with a symmetric antenna. Energy conversion between radiation power and electrical signals is utilized for the photovoltaic and photoconductive processes of the gold-graphene interface and biased electrodes, measuring a maximum photoresponsivity of 29.2mAW-1 . The generated photocurrent is altered under the polarization state of the input light, producing a 400% contrast between the maximum and minimum signals. This result is universally applicable to all on-chip optoelectronic circuits.

Self-powered deep ultraviolet PIN photodetectors with excellent response performance based on Ga2O3 epitaxial films grown on p-GaN

PIN-type self-powered deep ultraviolet (DUV) photodetectors (PDs) based on Ta doped n-Ga2O3/i-Ga2O3/p-GaN structures with different i-Ga2O3 layer thicknesses were prepared. In the structure, a Ta element in the doped Ga2O3 epitaxial layer should be substitutional doping, which can be confirmed by time-of-flight secondary ion mass spectrometry. With increasing thickness (0–90 nm) of the i-Ga2O3 layer, the crystal quality of the deposited epitaxial films is gradually improved, but the performance of corresponding PDs does not increase monotonically. The PD with an i-layer thickness of c.30 nm under zero bias shows the best response performance such as maximum photoresponsivity (8.67 A/W), good detectability (1.08 × 1014 Jones), and fast response/decay time (86/50 ms) under 222-nm-UV-light illumination. Such good performance should be attributed to the competition between the high photogenerated carriers and the low electric field, whereas the competition is caused by broadening of the depletion region. This research provides an improved and easy method for fabricating high-performance self-powered DUV PDs.

A Novel Approach for Designing a Sub-Bandgap in CuGa(S,Te)2 Thin Films Assisted with Numerical Simulation of Solar Cell Devices for Photovoltaic Application.

As a well-explored chalcopyrite material, copper gallium sulfide CGS has been considered a potential material for solar cell absorber layers. However, its photovoltaic attributes still require to be improved. In this research, a novel chalcopyrite material, copper gallium sulfide telluride CGST, has been deposited and verified as a thin film absorber layer to fabricate high-efficiency solar cells by experimental testing and numerical simulations. The results display the intermediate band formation in CGST with incorporation of Fe ions. Electrical studies showed enhancement in mobility from 1.181 to 1.473 cm2 V-1 s-1 and conductivity from 2.182 to 5.952 S cm-1 for pure and 0.08 Fe-substituted thin films. The I-V curves display the photoresponse and ohmic nature of the deposited thin films, and the maximum photoresponsivity (0.109 A W-1) was observed for 0.08 Fe-substituted films. Theoretical simulation of the prepared solar cells was carried out using SCAPS-1D software, and the obtained efficiency displayed an increasing trend from 6.14 to 11.07% as the Fe concentration increased from 0.0 to 0.08. This variation in efficiency is attributed to the decrease in bandgap (2.51-1.94 eV) and the formation of an intermediate band in CGST with Fe substitution, which is evidenced in UV-vis spectroscopy. The above revealed results open the way to 0.08 Fe-substituted CGST as a promising candidate as a thin film absorber layer in solar photovoltaic technology.

Metal Work Function Effects on the Performance of UV–Visible–NIR Cs2SnI6 Photodetectors for Flexible Broadband Application

Herein, the role of top metal electrode work functions on the performance of flexible broadband ultraviolet (UV)–visible–near‐infrared (NIR) flexible Cs2SnI6 (CSI) photodetectors (PDs) are reported in the present study. The change in crystal plane orientation, surface morphology, and chemical composition of prepared films compared to hydrothermally synthesized CSI particles is confirmed by physical characteristics tools. The optical bandgap of CSI films is estimated to be 1.36 eV. The flexible CSI PDs are fabricated with three top metal electrodes (Mo, Ti, and Ni). The current–voltage (I–V) characteristics under the illumination of light sources with different wavelengths reveal the broadband UV–visible–NIR photodetection properties of flexible CSI PDs. The device with top Ti electrodes demonstrates maximum photoresponsivity (Rph = 1.65 ± 0.45 A W−1) and specific detectivity (Dph = 4.53 ± 0.36) × 1010 Jones for 455 nm compared to other wavelengths at Vb = 5 V. The fast photoresponse/decay time is 18 ms/24 ms for 455 nm at Vb = 1 V. The 85% and 90%–95% retentions of Rph of devices after 12 days keeping in a desiccator and after 500 bending cycle tests suggest the device's good environmental stability and mechanical flexibility, respectively. Thus, it is indicated in the results that CSI materials can be a potential candidate for flexible UV–visible–NIR photodetector for wearable electronic device applications.

Multilayer WSe2/ZnO heterojunctions for self-powered, broadband, and high-speed photodetectors

Self-powered broadband photodetectors have attracted great interest due to their applications in biomedical imaging, integrated circuits, wireless communication systems, and optical switches. Recently, significant research is being carried out to develop high-performance self-powered photodetectors based on thin 2D materials and their heterostructures due to their unique optoelectronic properties. Herein, a vertical heterostructure based on p-type 2D WSe2 and n-type thin film ZnO is realized for photodetectors with a broadband response in the wavelength range of 300–850 nm. Due to the formation of a built-in electric field at the WSe2/ZnO interface and the photovoltaic effect, this structure exhibits a rectifying behavior with a maximum photoresponsivity and detectivity of ∼131 mA W−1 and ∼3.92 × 1010 Jones, respectively, under an incident light wavelength of λ = 300 nm at zero voltage bias. It also shows a 3-dB cut-off frequency of ∼300 Hz along with a fast response time of ∼496 μs, making it suitable for high-speed self-powered optoelectronic applications. Furthermore, the facilitation of charge collection under reverse voltage bias results in a photoresponsivity as high as ∼7160 mA W−1 and a large detectivity of ∼1.18 × 1011 Jones at a bias voltage of −5 V. Hence, the p-WSe2/n-ZnO heterojunction is proposed as an excellent candidate for high-performance, self-powered, and broadband photodetectors.

Linear photogalvanic effects in monolayer WSe2 with defects.

Linear photogalvanic effects in monolayer WSe2 with defects are investigated by non-equilibrium Green's function technique combined with density functional theory. Monolayer WSe2 generates photoresponse in the absence of external bias voltage, showing potential applications in low-power consumption photoelectronic devices. Our results show that the photocurrent changes in perfect sine form with the polarization angle. The maximum photoresponse Rmax produced in the monoatomic S substituted defect material is 28 times that of the perfect material when the photon energy is 3.1 eV irradiated, which is the most outstanding among all the defects. Monoatomic Ga substitution extinction ratio (ER) is the largest, and its ER value is more than 157 times that of the pure condition at 2.7 eV. As the defects concentration increases, the photoresponse is changed. The concentrations of Ga substituted defects have little effect on the photocurrent. The concentrations of Se/W vacancy and S/Te substituted defect have a great influence on the photocurrent increase. Our numerical results also show that monolayer WSe2 is a candidate material for solar cells in the visible light range and a promising polarization detector material.

Chiral metal-organic framework based spin-polarized flexible photodetector with ultrahigh sensitivity

Spin-optoelectronics plays a key role in developing next-generation technologies with potential applications covering from pharmaceutical synthesis and quantum computing to optical communication. One of the most feasible ways to achieve high-performance spin optoelectronic devices is based on chiral materials. Chiral metal-organic frameworks (CMOFs), an emerging class of chiral hybrid materials, have sparked interest due to their structural variety and flexibility, order nanopores, cost-effectiveness, and unique chirality features. Herein, we have developed CMOF [Sr (9,10-adc) (DMAc)2]n based on achiral building blocks [(9,10-adc)] to detect circularly polarized light (CPL) with ultrahigh sensitivity. Their application in spin-polarized flexible detectors gives a detectivity (D∗) as high as 1.83 × 1012 jones, superior to all reported heterochiral MOF-based detectors. Meanwhile, the anisotropy factor (gIph) is up to 0.38 for CPL detection. The maximum photoresponsivity (Rph) and photogain (η) values of CMOFs reach up to 6.0 × 105 (A/W) and 1.8 × 106, respectively, which are also the record values among reported chiral MOFs. Additionally, the photodetector is mechanically flexible and durable, manifesting an important feature for wearable devices. Therefore, our study shown here is significant and timely to open a route for advancing spin-optoelectronics based on CMOF.

Bi2Te2Se and Sb2Te3 heterostructure based photodetectors with high responsivity and broadband photoresponse: experimental and theoretical analysis.

Topological insulators have emerged as one of the most promising candidates for the fabrication of novel electronic and optoelectronic devices due to the unique properties of nontrivial Dirac cones on the surface and a narrow bandgap in the bulk. In this work, the Sb2Te3 and Bi2Te2Se materials, and their heterostructure are fabricated by metal-organic chemical vapour deposition and evaporation techniques. Photodetection of these materials and their heterostructure shows that they detect light in a broadband range of 600 to 1100 nm with maximum photoresponse of Sb2Te3, Bi2Te2Se and Sb2Te3/Bi2Te2Se at 1100, 1000, and 1000 nm, respectively. The maximum responsivity values of Sb2Te3, Bi2Te2Se, and their heterostructure are 183, 341.8, and 245.9 A W-1 at 1000 nm, respectively. A computational study has also been done using density functional theory (DFT). Using the first-principles methods based on DFT, we have systematically investigated these topological insulators and their heterostructure's electronic and optical properties. The band structures of Sb2Te3 and Bi2Te2Se thin films (3 QL) and their heterostructure are calculated. The bandgaps of Sb2Te3 and Bi2Te2Se are 26.4 and 23 meV, respectively, while the Sb2Te3/Bi2Te2Se heterostructure shows metallic behaviour. For the optical properties, the dielectric function's real and imaginary parts are calculated using DFT and random phase approximation (RPA). It is observed that these topological materials and their heterostructure are light absorbers in a broadband range, with maximum absorption at 1.90, 2.40, and 3.21 eV.