Visible Photoresponse Research Articles

Narrow Band Gap Base Metal Double Perovskite Oxides Through Copper Doping of Ba2Ca0.66Nb1.33O6

This work examines the influence of copper doping on the structure, optoelectronic properties, and photocatalytic performance of transition metal double perovskite oxides of the Ba2Ca0.67Nb1.33O6 (BCN) family. A solid-state synthesis method was used to achieve partial substitution of Cu2+ in the Nb5+ site (Ba2Ca0.67Nb1.33-xCuxO6-δ, x = 0.05, 0.13, 0.26) and Ca2+ site (Ba2Ca0.67-xCuxNb1.33O6-δ, x = 0.13). The incorporation of copper in BCN resulted in significant changes in the structure and optoelectronic properties. Major differences were observed when Cu atoms occupied the Nb-site versus the Ca-site. The parent compound and Ca-site doped compounds crystallized in a P3 1 space group while Nb-site doped compounds showed increasing Fm3 mixed phase character. Cu doping resulted in a dramatic shift of the absorption band edge towards the visible region. Ca-site doping resulted in a primary band edge shift from 3.8 eV to 2.1. For the Nb-site doped compounds, the primary band-edge remained at 3.8 eV but a secondary band-edge appeared which progressively shifted to smaller energies as Cu doping increased. Ba2Ca0.67Nb1.20Cu0.13O6-δ and Ba2Ca0.67Nb1.07Cu0.26O6-δ exhibited strong absorption of near-infrared photons of wavelength well beyond 800 nm. The double perovskite oxides were utilized as photoanodes for photoelectrochemical water splitting, exhibiting both a visible photoresponse (until wavelengths as low as 520 nm) and good photochemical stability. This work showcases the possibility of forming new low band gap multi-element inorganic semiconductor oxides constituted entirely of base metals and oxygen.

Photo-Electrochemical Oxygen Evolution Activity in Nickel and Cobalt Antimonates

Renewable generation of fuels via solar energy offers promising pathways towards sustainable energy future. Its deployment hinges on the discovery of electrochemically durable materials with good solar-to-chemical conversion efficiency. Necessary visible spectrum photoresponse from electrochemically stable materials is however quite rare. On the other hand, the oxygen evolution reaction (OER) requires electrodes that are not only catalytically active, but also stable under harsh electrochemical environments. In this talk, we report on and theoretical understanding of photo-electrochemical behavior an amorphous and crystaline versions of Ni-Sb-Ox and Co-Sb-Ox oxide photoanodes discovered via high-throughput experimental screening [1,2]. The newly discovered amorphous phases meet the requirements of operational stability, visible photoresponse, and appreciable photovoltage. Guided by experimental X-ray absorption characterization of these systems we use density functional theory calculations to perform a prototype phase search to identify a broad family of stable and metastable mixed rutile and hexagonal-like phases for other compositions [3]. Detailed Pourbaix analysis of the identified phases show excellent electrochemical stability, consistent with experimentally measured electrolyte concentrations of photoelectrochemical cells. We analyze when he identified phases form favorable oxygen vacancies formation energies under the reducing synthesis conditions which match measured Ni K-edge x-ray absorption spectra. The calculated OER overpotentials for the most active sites decreases with increasing Ni/Co content, which captures the experimentally observed trend. Stable amorphous metal-antimonates photoanodes are important systems for computational understanding of both the structural and catalytic behavior of these complex oxides and elucidating the co-optimization of photo-electrochemical activity and durability. This material is based on work performed by the Liquid Sunlight Alliance, which is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under award DE-SC0021266.[1] Zhou, L., Peterson, E. A., Rao, K. K., Lu, Y., Li, X., Lai, Y., Bauers, S. R., Richter, M. H., Kan, K., Wang, Y., Newhouse, P. F., Yano, J., Neaton, J. B., Bajdich, M., & Gregoire, J. M. Addressing solar photochemistry durability with an amorphous nickel antimonate photoanode. Cell Reports Physical Science, 3(7), 100959. (2022).[2] Zhou, L., Wang, Y., Kan, K., Lucana, D. M., Guevarra, D., Lai, Y., & Gregoire, J. M. Surveying Metal Antimonate Photoanodes for Solar Fuel Generation. ACS Sustainable Chemistry and Engineering, 21, 33. (2022).[3] Rao, K. K., Zhou, L., Lai, Y., Richter, M. H., Li, X., Lu, Y., Yano, J., Gregoire, J. M. Bajdich, M., Resolving Atomistic Structure and Oxygen Evolution Activity in Nickel Antimonates, (under review).

High self-powered UV–Visible photoresponse in ZnO/CuO heterostructure photodetectors, the influence of ZnO window layer thickness

In this study, we have fabricated ZnO/CuO heterostructure photodiodes on FTO substrate using the RF-sputtering method and investigated the influence of the ZnO thickness (390 and 470 nm) on their photoresponse in the wide range of UV to red wavelengths. The layers were characterized by FESEM, XRD, Raman, PL, and UV–Vis. Spectra, also I–V, I–V–T (295–340 K), and I-t in the dark and under illumination. We found: (1) the constituent layers have a polycrystalline nature, monoclinic phases for CuO and wurtzite phase for ZnO layers; (2) in addition to rectifying behavior, the I–V–T analysis confirmed that the current mechanism of these junctions follows the recombination model; (3) both samples have the potential of photovoltaic properties with self-powered ability; (4) sample with thinner ZnO layer has the highest photoresponse ratio (ILight/IDark) of 5.5 × 104–2.6 × 103 through UV to red light illumination and fast response time of 45–50 ms.

Al2O3 barrier layer for enhancing UV to visible rejection ratio in p-Si/n-MgZnO heterojunction visible blind UV photodetectors

The fabrication of visible blind ultraviolet photodetectors based on p-Si/n-MgxZn1-xO heterojunction is challenging due to the generation of visible photoresponse caused by the drift of visible light generated electrons from p-silicon to n-MgxZn1-xO across the interface. Here, it is shown that by incorporating a thin ∼30 nm Al2O3 interlayer at the heterojunction, the UV-to-visible rejection ratio in p-Si/n-Mg0.25Zn0·75O photodetectors can be significantly enhanced. The Al2O3 interlayer inserted between n-Mg0.25Zn0·75O and p-Si serves as an effective blocking layer against the transport of visible light-generated electrons from p-Si to n-Mg0.25Zn0·75O, thereby suppressing the visible photoresponse. As a result, the UV-to-visible rejection ratio was improved by approximately three orders of magnitude, with a peak responsivity of 0.17 mA/W at 270 nm and a reverse bias of 0.5 V. This high degree of visible blindness of p-Si/n-Mg0.25Zn0·75O heterojunction photodetectors with an Al2O3 barrier layer holds promise for next-generation visible-blind UV photodetection applications.

Fe Substitutions Improve Spectral Response of Bi2WO6-Based Photoanodes

The quest for a scalable solar fuel technology has stimulated a concerted effort to develop a metal oxide semiconductor for solar-driven photoelectrochemical water oxidation (oxygen evolution reaction) in an efficient and durable manner. So far, the search for such a metal oxide photoanode has highlighted the promise of Bi-based oxides, which have also been extensively studied for other photocatalyst applications. Bi2WO6 is a durable photocatalyst whose primary shortcoming is a 2.8 eV band gap that limits utilization of the solar spectrum. Improvements in visible photoresponse upon incorporation of Fe have been reported in the photocatalysis literature, motivating our use of high-throughput synthesis and photoelectrochemistry to determine the spectral photoresponse for Bi–W–Fe oxides synthesized under nonequilibrium conditions based on thermal oxidation of metallic films. Photoactivity down to 2 eV was achieved over a broad range of compositions, with detailed characterization of optimal compositions revealing that Fe incorporation increases the valence band position by 0.75 eV. Density functional theory calculations of Fe substitutions on W sites in Bi2WO6 are consistent with this valence band shift, providing a plausible explanation for the experiments. This Fe-mediated band tuning yields a ca. 2 eV band gap while retaining a turn-on potential for photoanodic current near 0.4 V versus RHE, which combined with the operational durability motivates continuous study and development of this promising class of metal oxide photoanodes.

Blocking Si‐Induced Visible Photoresponse in n‐MgxZn1–xO/p‐Si Heterojunction UV Photodetectors Using MgO Barrier Layer

Photodetectors based on n‐Mg0.25Zn0.75O/p‐Si heterojunctions are not only suitable for integration with existing semiconductor technology, but also circumvent the difficulty of stable p‐type doping in MgxZn1–xO. However, the use of Si leads to photoresponse in the visible part of the light spectrum, which renders n‐MgxZn1–xO/p‐Si heterojunction devices unsuitable for visible blind UV photodetection. Herein, it is demonstrated that the visible photoresponse in the n‐Mg0.25Zn0.75O/p‐Si photodetectors can be significantly suppressed by inserting a thin interlayer of MgO at the heterojunction. The MgO layer serves as a blocking layer for the drift of photo‐excited electrons from p‐Si to n‐Mg0.25Zn0.75O, thereby limiting the visible photoresponse. It is found that on increasing the thickness of the MgO interlayer from 3 to 15 nm, the UV to visible rejection ratio increases from ≈25 to 200. This enhancement in the UV to visible rejection ratio demonstrates that n‐Mg0.25Zn0.75O/p‐Si heterojunction devices with MgO interlayer are promising for visible‐blind UV photodetection applications.

Ultraviolet and visible photo-response of transparent conductive Al-doped ZnO (AZO)/n-Silicon isotype heterojunction device

In this work, the electrical and photoresponse measurements of a transparent conductive Al-doped ZnO (AZO)/n-Si heterojunction device were conducted in visible light and UV wavelengths. AZO film was deposited by sputtering onto an n-Si wafer and investigated by means of morphological, chemical and electrical characterizations. The AZO/n-Si rectifying device exhibits an excellent reproducibility without noticeable variations after 90 days of measurements. At self-powered mode, the maximum on/off ratios were determined as 3081 for visible light and 4778 for UV light illumination of 365 nm. The responsivity and detectivity of the AZO/n-Si photodetector were 0.128 A W−1 and 1.05 × 1011 Jones for 365 nm, whereas they were 0.055 A W−1 and 4.60 × 1010 Jones for 395 nm, respectively (at −2.0 V). This study demonstrated that the n-AZO/n-Si isotype heterojunction photodetector was fabricated at low cost and it is a potential candidate in both the visible region and the UV region with a good performance, in contrast to the widely studied pn heterojunctions.

Negative photoresponse in Ti3C2T x MXene monolayers

Abstract Two-dimensional transition metal carbides, nitrides, and carbonitrides, collectively known as MXenes, are finding numerous applications in many different areas, including optoelectronics and photonics, but there is limited information about their intrinsic photoresponse. In this study, we investigated the visible and near-infrared range photoresponse of Ti3C2T x , the most popular MXene material to date. The electrical measurements were performed on devices based on individual monolayer Ti3C2T x MXene flakes, which were characterized by a variety of microscopic and spectroscopic methods. For MXene devices with different electrode layouts, the current reproducibly decreased under illumination with either white light or lasers with different wavelengths in the visible and near-infrared region, thus demonstrating a negative photoresponse. The understanding of the intrinsic photoresponse of Ti3C2T x should facilitate the optoelectronic and photonic applications of MXenes.

Addressing solar photochemistry durability with an amorphous nickel antimonate photoanode

Renewable generation of fuels using solar energy is a promising technology whose deployment hinges on the discovery of materials with a combination of durability and solar-to-chemical conversion efficiency that has yet to be demonstrated. Stable operation of photoanodes has been demonstrated with wide-gap semiconductors, as well as protected visible gap semiconductors. Visible photoresponse from electrochemically stable materials is quite rare. In this paper, we report the high-throughput discovery of an amorphous Ni-Sb (1:1) oxide photoanode that meets the requirements of operational stability, visible photoresponse, and appreciable photovoltage. X-ray absorption characterization of Ni and Sb establishes a structural connection to rutile NiSb 2 O 6 , guiding electronic structure characterization via X-ray photoelectron experiments and density functional theory. This amorphous photoanode opens avenues for photoelectrode development due to the lack of crystal anisotropy combined with its operational stability, which mitigates the formation of an interphase that disrupts the semiconductor-electrolyte junction. • High-throughput experiments enable the discovery of an amorphous Ni-Sb photoanode • Favorable Pourbaix energetics and amorphous surface provide excellent durability • The broad spectral response stands in contrast to end members Sb 2 O 5 and NiO • Electronic and chemical structure characterization pave the way for future study Harvesting solar energy to sustainably synthesize fuels requires the identification of materials that can operate durably for many years. Inspired by the corrosion resistance of amorphous oxides, Zhou et al. report an amorphous nickel antimonate with visible light photoactivity and lower corrosion than analogous materials, paving a pathway for further technology development.

Visible photoresponse of TiO2 nanotubes in comparison to that of nanoparticles and anodic thin film

Reports on the defective anodic titanium dioxide (TiO2) that harvests solar energy to perform photochemical reactions generating value-added chemicals and/or energy are scarce. In this study, we synthesize TiO2 with two different morphologies (i.e., nanotube and compact layer) on a Ti substrate in a fluoride- and sulfide-containing electrolyte by using the electrochemical anodization method. The effect of high-temperature annealing on various TiO2 structures and substrates in comparison with commercial TiO2 nanoparticles coated on fluorine-doped tin oxide substrate under different gaseous environments (i.e., Ar, air, and O2) is investigated herein by virtue of crystallinity, optoelectronic-physical properties, and photoelectrochemical performances. Unlike traditional TiO2 nanoparticles, which are only active in ultraviolet illumination and with severe aggregation, the anodic TiO2 nanotubes endow the effect of the oxygen vacancy and the self-doping of F− and S− ions upon annealing under the Ar environment, which is crucial to extending the photoresponse to the visible region. The gray anodic TiO2 obtained through thermal annealing at 450 °C crystallizes in the anatase phase and maintains an intact surface morphology under different gaseous environments. The electron paramagnetic spectra are used to confirm the presence of Ti3+ or oxygen vacancy. The entrapment of the F− and S− ions within TiO2 is determined by X-ray photoelectron spectroscopy and energy-dispersive spectroscopy introducing intrinsic defect states, which can resolve the bottlenecks in materials and encourages new paradigms beyond solar light-induced photocatalysis.

Simultaneous visible and ultraviolet photoresponse improvement of MoS2/ZnO heterostructure photodetector via direct resonant coupling of Au nanoparticles localized surface plasmon resonance

Localized surface plasmon resonance (LSPR) as a unique property of metal nanoparticles (NPs) has been widely applied to enhance the performance of optoelectronic devices. However, limited by the specific resonance frequency of plasmonic NPs, the LSPR of NPs can only improve the photoresponse performance of photodetectors at specific wavelength. In this work, a simple strategy is proposed to simultaneously improve the performance of the p-MoS2/n-ZnO heterostructure photodetector in visible and ultraviolet (UV) light regions by modifying Au NPs. The Ilight/Idark ratio of the photodetector is considerably increased after the functionalization with plasmonic Au NPs under visible and UV light illumination due to the direct resonant coupling of LSPR. In particular, the photocurrent of the photodetector increases 14.8 times after Au NPs modification under 532 nm illumination, giving rise to an obvious increase in responsivity, external quantum efficiency and specific detectivity. Moreover, the modification of Au NPs facilitates the rapid separation of electrons and holes due to the generation of surface depletion regions located at Au/MoS2 and Au/ZnO interfaces. Consequently, the photoresponse speed is also drastically improved after Au NPs decoration in both visible and ultraviolet light regions. The strategy of direct resonant coupling of Au NPs LSPR with two photosensitive materials proposed in this work will provide a new avenue for optimizing the performance of optoelectronic devices.

Development of 2D based ZnO–MoS2 nanocomposite for photodetector with light-induced current study

Composites of 2D transition metal dichalcogenides and metal oxides give suitable UV–Visible photoresponse properties. Here, in our research work, the preparation of ZnO–MoS2 nanocomposite is done via a two-step sol-gelassisted cost-effective, and facile synthesis method. The optical bandgap of the as-prepared nanocomposite was found to be 3.68 eV. X-ray diffractogram revealed the crystalline nature of the as-prepared nanocomposite. The optical properties of the material were investigated using Ultraviolet–Visible spectroscopy (UV–Visible) and Fourier Transform Infrared (FTIR) spectroscopy. Surface morphological studies were performed by Scanning electron microscopy (SEM) and the elemental investigations were carried out by the Energy Dispersive X-ray spectroscopy (EDS). For the as-prepared nanomaterial, photoresponsivity was found to be 34.50 mA/W, specific detectivity was 2.36 × 1010 Jones, and response time was found to be 2.46 s at the applied drift potential of 5 V.

ZnO nanorods coating modified with AgInS2 quantum dots

This paper presents the effect on the visible light photoresponse caused by the modification of ZnO nanorod coating with colloidal AgInS2 quantum dots. The modification of ZnO nanorods by immersion in colloidal solution results in the enhancement of visible absorption and photoresponse. Obtained results indicate the possibility of local heterojunctions between ZnO and AgInS2.

Rapid organic dye degradation and wavelength dependent sensing study in Cu1-xFexO

Cu1-xFexO (x = 0, 0.0156, 0.0234 and 0.0312) nanoparticles have been synthesized by using a simple sol-gel route. A pure monoclinic phase (space group c2/c) was observed from XRD studies. A Rietveld analysis of the XRD spectra using GSAS software helped evaluate the variations of lattice constant, lattice strain and bond length/angles. With Fe doping, while the indirect bandgap could be nominally tuned from ∼1.40 eV to ∼1.46 eV, the Fe-doping seems to improve carrier concentration, mobility, and lattice regularity than pure CuO. The photocatalytic degradation of toxic methylene blue (MB) dye could be enhanced from 0.91%/min for the pure CuO to 1.48%/min for 3.125%-Fe-doped CuO. This property has been correlated to the carrier properties of the materials. The UV and visible photoresponse of Cu1-xFexO nanoparticles was investigated. A drastic reduction in both UV and visible light-sensitivity with Fe-doping was observed and correlated with carrier properties.

Fast-speed self-powered PEDOT:PSS/α-Ga2O3 nanorod array/FTO photodetector with solar-blind UV/visible dual-band photodetection

The α-Ga2O3 nanorod array is grown on FTO by hydrothermal and annealing processes. And a self-powered PEDOT:PSS/α-Ga2O3 nanorod array/FTO (PGF) photodetector has been demonstrated by spin coating PEDOT:PSS on the α-Ga2O3 nanorod array. Successfully, the PGF photodetector shows solar-blind UV/visible dual-band photodetection. Our device possesses comparable solar-blind UV responsivity (0.18 mA/W at 235 nm) and much faster response speed (0.102 s) than most of the reported self-powered α-Ga2O3 nanorod array solar-blind UV photodetectors. And it presents the featured and distinguished visible band photoresponse with a response speed of 0.136 s at 540 nm. The response time is also much faster than the other non-self-powered β-Ga2O3 DUV/visible dual-band photodetectors due to the fast-speed separation of photogenerated carries by the built-in electric field in the depletion regions of PEDOT:PSS/α-Ga2O3 heterojunction. The results herein may prove a promising way to realize fast-speed self-powered α-Ga2O3 photodetectors with solar-blind UV/visible dual-band photodetection by simple processes for the applications of multiple-target tracking, imaging, machine vision and communication.

Anisotropic Properties of Quasi‐1D In4Se3: Mechanical Exfoliation, Electronic Transport, and Polarization‐Dependent Photoresponse

AbstractTheoretical and experimental investigations of various exfoliated samples taken from layered In4Se3 crystals are performed. In spite of the ionic character of interlayer interactions in In4Se3 and hence much higher calculated cleavage energies compared to graphite, it is possible to produce few‐nanometer‐thick flakes of In4Se3 by mechanical exfoliation of its bulk crystals. The In4Se3 flakes exfoliated on Si/SiO2 have anisotropic electronic properties and exhibit field‐effect electron mobilities of about 50 cm2 V−1 s−1 at room temperature, which are comparable with other popular transition metal chalcogenide (TMC) electronic materials, such as MoS2 and TiS3. In4Se3 devices exhibit a visible range photoresponse on a timescale of less than 30 ms. The photoresponse depends on the polarization of the excitation light consistent with symmetry‐dependent band structure calculations for the most expected ac cleavage plane. These results demonstrate that mechanical exfoliation of layered ionic In4Se3 crystals is possible, while the fast anisotropic photoresponse makes In4Se3 a competitive electronic material, in the TMC family, for emerging optoelectronic device applications.

Ultraviolet, visible and near infrared photoresponse of SiO2/Si/SiO2 multilayer system into a MOS capacitor

In this paper, we report on the photoresponse properties of a SiO2/Si/SiO2 multilayer (ML) system deposited at 500 °C and integrated into a metal-oxide-semiconductor structure (Al/ML/p-Si) without any further thermal annealing. High contents of elemental Si (Si0) revealed by the XPS measurements suggests the formation of amorphous Si-nanoclusters (a-Si ncls) within the ML. Dark and illuminated I–V curves of the device indicate its sensitivity to ultraviolet, visible and near infrared light under applied bias and at 0 V. In addition, we observed variation of the spectral response and the external quantum efficiency as a function of the electrode size. At 0 V, the device illuminated with a wavelength at 550 nm exhibits a maximum external quantum efficiency of 0.95% and a spectral response of 4.1 mA/W. This photoresponse has been ascribed to photon absorption in SiO2 sub-band states created by the a-Si ncls and defects formed by the excess Si inside the SiO2/Si/SiO2 multilayers.

Microstructured ZnO-ZnS composite for earth-abundant photovoltaics: Elaboration, surface analysis and enhanced optical performances

In this paper, ZnO-ZnS composite structure is proposed as a new efficient and earth-abundant absorber material for thin-film solar cells (TFSCs). Promising elaboration strategy based on combining vacuum thermal evaporation technique and oxidation process under an annealing temperature of 500 °C was used to prepare ZnO-ZnS composite with high sun-light absorption capabilities. The fabricated microstructure was then characterized by Scanning Electron Microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and UV–Visible absorption spectroscopy. The influence of the annealing time on the structural and optical performances of the prepared samples was investigated. Surface analysis demonstrated the ZnO decoration of ZnS thin-film, where SEM images showed dense and pinhole-free ZnO-ZnS composite with micrometer-sized grains and a few voids visible at thin-films surface. Optical characterization showed that the prepared thin-film absorber exhibits an optical band-gap of 2.65 eV with a high Total Absorption Efficiency (TAE) of 62% and an absorption coefficient exceeding 2 × 104 cm−1. In addition, I-V characteristics under dark and 1-sun illumination of the microstructured ZnO-ZnS composite were extracted. It was revealed that the proposed absorber showcases a high visible photoresponse. Therefore, promoting effective light-scattering effects, this innovative ZnO-ZnS composite offers a sound pathway to prepare alternative low-cost absorbers for the future development of TFSCs.

Visible light photoconductivity studies of gold nanoparticle embedded ZnO thin films for photo detector application

This report demonstrates the visible photo response of gold nanoparticles (AuNPs) embedded ZnO nanocomposite (AuNPs-ZnO) thin films. The AuNPs-ZnO films were prepared by sandwiching DC sputtered AuNPs in between two RF sputtered ZnO layers deposited on p-Si. Crystal phase purity and surface morphology were characterized by the x-ray diffraction and scanning electron microscope. The formation of AuNPs was confirmed by observing the plasmonic dip in optical transmittance. Photoconductivity study was done by recording current–voltage characteristics of the films in the presence of visible light. The ratio of light to dark current was found to be enhanced by two to three orders of magnitude with the inclusion of AuNPs. The observed photocurrent enhancement was found to vary with both AuNPs concentration and sandwich thickness. The highest responsivity observed with the fabricated nanocomposite films was of 0.012 A W−1. The dominant reason for the visible photoconductivity and for the enhancement in photocurrent was ascribed to the plasmonic properties of AuNPs-ZnO composite film. This study paves a new approach to design and fabricate devices for optoelectronic applications.

Visible range photoresponse of vertically oriented on-chip MoS2 and WS2 thin films

The excellent electrical properties of transition metal dichalcogenide (TMD) 2D materials promise a competitive alternative to traditional semiconductor materials for applications in optoelectronics, chemical sensing, as well as in energy harvesting and conversion. As the typical synthesis methods of TMDs produce nanoparticles, such as single or multi-layered nanoflakes, subsequent strenuous integration steps are necessary to obtain devices. Direct synthesis of the material on substrates would simplify the process and provide the means for large-scale integration and production of practical devices. In our approach, we synthesize MoS2 and WS2 thin films with a simple sulfurization of the respective metal films deposited by sputtering on Si/SiO2 chips, and study their optoelectrical properties at wavelengths of 661 nm, 552 nm, and 401 nm using pulsed lasers. Both TMD thin films are found to show photoresponsivities of up to ∼5 × 10−6 A W−1 with corresponding quantum efficiencies of ∼10−5, which are unexpectedly moderate, and can be attributed to their columnar microstructure, in which the basal planes of the hexagonal lattices are perpendicular to the substrate, thus, limiting the electron transport in the films parallel to the plane of the substrate.