Photocurrent Of Device Research Articles

Flexo-Phototronic Boosted Self-Powered Ultraviolet Detection in ZnAl:Layered Double Hydroxide Nanosheets/NiO Heterostructure.

Developing self-powered and flexible optoelectronic sensors with high responsivity and speed is crucial for modern applications, motivating continuous efforts to enhance their performance. Flexo-phototronics is a less-explored but promising technique to elevate the performance of optoelectronics. Therefore, this work addresses the potential of utilizing the flexo-phototronic effect to enhance the performance of a flexible and self-powered ultraviolet photodetector (UV PD) based on ZnAl:LDH (layered double hydroxides) nanosheets (Ns)/NiO heterostructure. The vertically oriented ZnAl:LDH Ns are synthesized via a simple method involving the immersion of a sputtered 10% Al-doped ZnO thin film in deionized water at room ambient conditions. The fabricated PD exhibits an impressive response to 365 nm UV light, with high sensitivity in the order of 103. The device's photocurrent and responsivity are significantly enhanced by the flexo-phototronic effect, attributed to the flexoelectric properties of ZnAl:LDH Ns. Specifically, applying an inhomogeneous tensile strain of 2% boosted the device responsivity by 57.1% and improved its operational speed. Furthermore, a working model revealing the altered energy-band structure is demonstrated to elucidate the flexo-phototronic-induced boost in the photoresponse. The PD also demonstrated a sustainable performance under severe bending cycles, underlining the good flexibility of the device. The results presented in this study demonstrate a self-powered and flexible UV PD and provide a viable approach to augment the performance of optoelectronics through the flexo-phototronic effect.

Octupole moment driven free charge generation in partially chlorinated subphthalocyanine for planar heterojunction organic photodetectors

In this study, high-performance organic photodetectors are presented which utilize a pristine chlorinated subphthalocyanine photoactive layer. Optical and optoelectronic analyses indicate that the device photocurrent is primarily generated through direct charge generation within the chlorinated subphthalocyanine layer, rather than exciton separation at layer interfaces. Molecular modelling suggests that this direct charge generation is facilitated by chlorinated subphthalocyanine high octupole moment (−80 DÅ2), which generates a 200 meV shift in molecular energetics. Increasing the thickness of chlorinated subphthalocyanine leads to faster response time, correlated with a decrease in trap density. Notably, photodetectors with a 50 nm thick chlorinated subphthalocyanine photoactive layer exhibit detectivities approaching 1013 Jones, with a dark current below 10−7 A cm−2 up to −5 V. Based on these findings, we conclude that high octupole moment molecular semiconductors are promising materials for high-performance organic photodetectors employing single-component photoactive layer.

Optical and Electrical Properties of AlGaN-Based High Electron Mobility Transistors and Photodetectors with AlGaN/AlN/GaN Channel-Stacking Structure.

High channel current of the high electron mobility transistors (HEMTs) and high relative responsivity of the photodetectors (PDs) were demonstrated in the AlGaN/AlN/GaN channel-stacking epitaxial structures. The interference properties of the X-ray curves indicated high-quality interfaces of the conductive channels. The AlGaN/AlN/GaN interfaces were observed clearly in the transmission electron microscope micrograph. The saturation I ds currents of the HEMT structures were increased by adding a number of channels. The conductive properties of the channel-stacking structures corresponded to the peaks of the transconductance (g m) spectra in the HEMT structures. The depletion-mode one- and two-channel HEMT structures can be operated at the cutoff region by increasing the reverse V gs bias voltages. Higher I ds current in the active state and lower current in the cutoff state were observed in the two-channel HEMT structure compared with one- and three-channel HEMT structures. For the channel-stacking metal-semiconductor-metal photodetector structures, the peak responsivity was observed at almost 300 nm incident monochromic light, which was increased by adding a number of channel layers. The channel current of the HEMT devices and the photocurrent in the PD devices were increased by adding a number of two-dimensional electron gas (2DEG) channels. By using a flat gate metal layer, the two-channel AlGaN/AlN/GaN HEMT structures exhibited a high I ds current, a low cutoff current, and a high peak g m value and have the potential for GaN-based power devices, fast portable chargers, and ultraviolet PD applications.

High-performance Ga2O3 solar-blind UV photodetectors via film growth regulation and surface state engineering

Gallium oxide (Ga2O3) with a wide bandgap is emerging as one of the most promising candidates for solar-blind photodetectors (SBPDs). However, the practical application of Ga2O3-based SBPDs is impeded by substantial defects-related leakage currents, sluggish response speed, and high-cost, making their practical applications face great challenges. Here, we proposed strategic films growth regulation and surface state engineering to grow high-quality yet economical β-Ga2O3 films, thereby achieving high-performance SBPDs. High-resolution transmission electron microscopy revealed the presence of high-quality films with an extremely regular arrangement of β-Ga2O3 (2‾01) planes. The full width at half maximum and root mean square roughness values are 0.07° and 0.716 nm, respectively. The β-Ga2O3 films demonstrated a significant reduction in VO concentrations after O2/N2 plasma treatment. This process can effectively minimize thermal damage to the sample surface while retaining highly reactive free radicals. The photocurrents of devices can be further enhanced, leading to a larger PDCRs of 8.6 × 107, through N2 plasma treatment. Moreover, the films effectually suppress the persistent photoconductivity effect with τr and τd values of 5.31/0.97 s and 0.49/0.87 s before and after N2 plasma treatment, respectively. We have demonstrated the influence mechanism of O2/N2 plasma treatment on photoelectronic performance. This study provides a practical approach to growing high-quality β-Ga2O3 films and preparing high-performance but low-cost Ga2O3-based SBPDs.

Infrared photodetection in graphene-based heterostructures: bolometric and thermoelectric effects at the tunneling barrier

Graphene/hBN/graphene tunnel devices offer promise as sensitive mid-infrared photodetectors but the microscopic origin underlying the photoresponse in them remains elusive. In this work, we investigated the photocurrent generation in graphene/hBN/graphene tunnel structures with localized defect states under mid-IR illumination. We demonstrate that the photocurrent in these devices is proportional to the second derivative of the tunnel current with respect to the bias voltage, peaking during tunneling through the hBN impurity level. We revealed that the origin of the photocurrent generation lies in the change of the tunneling probability upon radiation-induced electron heating in graphene layers, in agreement with the theoretical model that we developed. Finally, we show that at a finite bias voltage, the photocurrent is proportional to either of the graphene layers heating under the illumination, while at zero bias, it is proportional to the heating difference. Thus, the photocurrent in such devices can be used for accurate measurements of the electronic temperature, providing a convenient alternative to Johnson noise thermometry.

Embedding biocatalysts in a redox polymer enhances the performance of dye-sensitized photocathodes in bias-free photoelectrochemical water splitting

Dye-sensitized photoelectrodes consisting of photosensitizers and molecular catalysts with tunable structures and adjustable energy levels are attractive for low-cost and eco-friendly solar-assisted synthesis of energy rich products. Despite these advantages, dye-sensitized NiO photocathodes suffer from severe electron-hole recombination and facile molecule detachment, limiting photocurrent and stability in photoelectrochemical water-splitting devices. In this work, we develop an efficient and robust biohybrid dye-sensitized NiO photocathode, in which the intermolecular charge transfer is enhanced by a redox polymer. Owing to efficient assisted electron transfer from the dye to the catalyst, the biohybrid NiO photocathode showed a satisfactory photocurrent of 141±17 μA·cm−2 at neutral pH at 0 V versus reversible hydrogen electrode and a stable continuous output within 5 h. This photocathode is capable of driving overall water splitting in combination with a bismuth vanadate photoanode, showing distinguished solar-to-hydrogen efficiency among all reported water-splitting devices based on dye-sensitized photocathodes. These findings demonstrate the opportunity of building green biohybrid systems for artificial synthesis of solar fuels.

Size tunable and controllable synthesis of PbS quantum dots for broadband photoelectric response

PbS quantum dots (QDs) with size-dependent photoelectric characteristics and wide spectral absorption show a great potential material for preparing near-infrared photodetectors, attracting numerous studies. This paper prepared size-tunable PbS QDs with a mean size varying from 3 nm to 9 nm via a modified hot injection method. And the effects of different factors on the size of PbS QDs in the synthesis were systematically summarized. Moreover, size-dependent optoelectronic properties of PbS QDs were studied. With the increase in size, the dark current, photocurrent, and responsivity of devices show an increase, while the 3 dB bandwidth decreases. In addition, the larger the size, the wider the detection spectrum coverage, the detectivity of the corresponding absorption peak in PbS QDs is better than another size PbS QDs, but the maximum detectivity of the large size PbS QDs is lower than that of the small size PbS QDs in the near-infrared. Therefore, selecting different PbS QDs to prepare photodetector is of great significance for practical applications with different detection requirements. Significantly, these size-tunable PbS QDs photodetectors show fast response and excellent responsivity, and detectivity.

Enhanced Photocurrent in Ferroelectric KNNS-BNN Materials via Temperature Modulation

The photocurrent produced by the synergy of pyroelectric and photovoltaic effects in ferroelectric materials exhibits great potential for photodetection. Photocurrent generated by various ferroelectric materials exhibits a different behavior with the ambient circumstance especially the temperature, making it a long-term topic. Here, we report a remarkable promotion in the photocurrent of a photoelectric device based on ferroelectric (K0.5Na0.5)(Nb0.94Sb0.06)O3-Bi(Ni0.33Nb0.67)O3 (KNNS-BNN) materials via temperature modulation. When compared with the photocurrents obtained at room temperature, by lowering the atmospheric temperature to 14.8 °C, the peak photocurrent is increased by 219%, and by raising the temperature to 46 °C, the platform photocurrent is improved by 69.9%. The enhanced photocurrents are mainly ascribed to temperature-controlled conductivity and energy band structure of the KNNS-BNN materials. Working as a self-powered photodetector, the responsivity of the device reaches 4.01 × 10–6 A W–1. This work provides new possibilities for high-performance ferroelectric photodetectors.

Selenium-sensitized TiO2 p-n heterojunction thin films with high resistance to oxidation and moisture for self-driven visible-light photodetection

Semiconductor-sensitized TiO2 thin films have been widely applied in optoelectronic devices. Here we prepared narrow bandgap (∼1.77 eV) selenium (Se)-sensitized TiO2 thin films by spin-coating of Se inks onto a TiO2 mesoporous layer, which forms a p-Se/n-TiO2 heterojunction interface and holds promise for self-driven visible-light detection and sensing. Under irradiation by simulated sunlight and monochromatic visible-light, the resultant films exhibit large on-off switch ratio, fast response speed, and high spectral responsivity and detectivity at zero bias. Meantime, the p-Se/n-TiO2 films show notable photoresponse stability and can maintain 92% and 64% of photocurrent of the pristine device after 2-month air storage and 72 h water soaking, respectively. Such good oxygen and moisture resistance of Se/TiO2 thin films would be promising as applied in environmentally-stable heterojunction optoelectronic devices.

In Operando Quantification of Single and Multiphoton Photocurrents in GaP and InGaN Photodetectors with Phase-Modulated Femtosecond Light Pulses

Single and multiphoton absorptions in wide band gap semiconductors determine the functionality of photodetectors, lasers, and light-emitting diodes (LEDs). Although electronic structure strongly influences the different orders of multiphoton absorptions in semiconductors, it has not been feasible to quantify their contributions on the functionality of devices. A lack of proper measurement techniques has been the hurdle. Here, we present a simple and sensitive method based on the phase modulation of femtosecond pulses to quantify single-, two-, and three-photon absorptions in GaP and InGaN photodetectors. Our results show that only three-photon absorption contributes to the photocurrent in the InGaN device when excited by femtosecond pulses at 1030 nm. On the other hand, single-, two-, and three-photon absorptions have comparable contributions in the GaP detector. The three contributions have different origins: linear photocurrent is attributed to the absorption by the impurities in the doped regions, two-photon photocurrent is from the phonon-assisted indirect transition from the valence band to the conduction band minimum, and three-photon photocurrent is from the direct transition to the conduction band. We also demonstrate that the method can be applied to image the heterogeneity of multiphoton photocurrent in devices. Our work could be adapted for “in operando” characterization of optoelectronic systems.

A Tunable Polarization Field for Enhanced Performance of Flexible BaTiO3@TiO2 Nanofiber Photodetector by Suppressing Dark Current to pA Level

AbstractThe flexible titanium dioxide (TiO2) nanofibers (NFs) film are promising candidates for high‐performance wearable optoelectronic devices. However, the TiO2 ultraviolet photodetectors (UV PDs) generally suffer from low photosensitivity, which limits the practical applications. Herein, a TiO2 (TO) NFs film flexible photodetector integrated by ferroelectric BaTiO3 (BTO) NFs is developed via electrospinning technology with double sprinklers and in situ heat treatment. Compared with TO NFs PD with poor on/off ratio ≈44, the BTO@TO NFs PD‐2 exhibits an excellent on/off ratio of ≈1.5 × 104 due to the dramatically restrained dark current. The ultralow dark current (pA level) is attributed to the depletion of photogenerated carriers by the space high‐resistance state induced by the downward self‐polarization field in ferroelectric BaTiO3 NFs. The ferroelectric domain with larger downward orientation in polarized BTO@TO NFs exhibits stronger self‐polarization field to modify the directional transport of photogenerated carriers and enhances the band bending level, which improves the photocurrent of device. The special structure woven by ferroelectric nanofiber with self‐polarization will provide a promising approach for improving the performance of flexible photodetectors.

Perovskite Films Doped with Polyoxometalate and Ionic Liquid Assisted Crystallization for Efficient Photodetectors

AbstractThe dependence of perovskite‐based photovoltaic devices on toxic solvents limits their applications. Therefore, we added polyoxometalates into ionic liquids, as the green solvent and polyoxometalates synergistically improve the performance of devices. Firstly, methylammonium formate (MAFa) as solvent delayed the crystallization process of perovskite thin films, thus obtained an extended crystal domain, and the photocurrent of the device was increased from 35.51 μA to 63.18 μA. Secondly, introducing PW12 into this green solvent system, the matched energy level and good electron transmission rate promoted the separation of photogenerated excitons and accelerated the transmission of photogenerated electrons in perovskite. After dual adjustment of MAFa and PW12, the photocurrent of the champion device reached 95.99 μA (about 2.7 times of the original device), the unpacked devices can still maintain 80 % of initial value after being placed under environmental conditions for 700 h.

Improving the performance of the self-powered polymer-based UV/Vis photodetectors via carbon fibers

Both Polyvinylpyrrolidone (PVP) and matrix-polymer of carbon (C)-PVP fibers (Fs) composites were synthesized by using the electrospinning technique and deposited onto the p-Si wafers to obtain PVP Fs/p-Si and C-PVP Fs/p-Si devices. The ultraviolet/Visible (UV/Vis) photodetector performance of both devices was compared. Both devices gave self-powered mode and with increasing the visible light intensity, the photocurrents of both devices increased. Besides, it was observed that the optical performance of the device containing C was better than the PVP Fs/p-Si device in both visible and UV lights. This was attributed to the high absorption properties of carbon and the increase in conductivity in the PVP due to carbon fibers. Furthermore, it is thought that the electric field formed in the carbon-PVP interaction and C-PVP/p-Si interface improves the optical properties of the device by increasing the exciton separation efficiency. Under the self-powered mode, the C-PVP Fs/p-Si device exhibited a maximum detectivity and ON/OFF ratio of 5.60 × 1010 Jones and 53 764, respectively for UV light of 365 nm. Under 100 mW visible light, these values ​​were determined as 1.01 × 1010 Jones and 9739, respectively, at V = 0. In addition, from the obtained noise-equivalent power (NEP) values, it was concluded that weaker signals can be detected under UV light (6.94 × 10−14 w Hz−1/2, at −2 V) than visible light (3.32 × 10−13 w/Hz1/2, at −2 V) for C-PVP Fs/p-Si.

Low-cost novel X-shaped hole transport materials for efficient perovskite solar cells: Molecular modelling of the core and schiff base effects on photovoltaic and photophysical properties

Eight molecules with D-π-D molecular motifs coded HTM(1-4)a,b were designed as efficient symmetric hole transporting materials for perovskite solar cells. These HTMs are composed of different core moieties, such as spiro [fluorene-9,9′-xanthene]-diol (SFO), spiro [fluorene-9,9′-xanthene]-dimethoxy (SFM), benzo [c][1,2,5]thiadiazole (BTD), and biphenyl (BP) and are gaining lot of attention because of their low-cost, reproducible electrical and optical properties in device performance. Detailed information about the energetic of molecular levels (GSOP/ESOP), first singlet excitation energy (E0-0), equilibrium molecular geometry, charge separation, charge transfer, reorganization energies, polarizability and hyperpolarizability, density of states (DOS), solubility and stability of these molecules was attained by systematically performing molecular modeling calculations using density functional theory (DFT) and time dependent-DFT calculations utilizing hybrid density functional B3LYP using the basis set 6–31g(d,p) level of theory as a successful method for predicting the photophysical and photovoltaic properties of these conjugated systems. The results showed that not only the core moieties, but also Schiff-base linkage extended conjugation, have an effect on the photophysical and photovoltaic properties of the proposed HTMs. It was demonstrated that HTMs incorporating SFO (HTM1a,b), SFM (HTM2a,b), and BP (HTM4a,b) achieved better charge transport, high stability values (ηa = 2.11–2.40 eV), low electron-hole binding energy (Eb = 0.16–0.21 eV) than HTM3a,b with BTD core, which improves hole mobility and decreases recombination, all of which improved device photocurrent, which can be attributed to the extended π-conjugation in SFO, SFM and BP cores. These findings are strikingly similar to those of Spiro-OMeTAD (ηa = 2.45 eV, Eb = 0.16 eV), indicating that these HTMs are promising candidates for efficient and cost-effective PSCs. Interestingly, when the stability of HTM(1-4)a and HTM(1-4)b was compared, it was clear that HTM(1-4)a has lower stability than HTM(1-4)b, which could be attributed to the presence of Schiff base CN bonds in HTM(1-4)b, which reduces the molecules stability when compared to HTM(1-4)b, owing to a strong C–C linkage. Meanwhile, HTM(1-4)a outperforms HTM(1-4)b in terms of electronic performance and hole mobility.

Van der Waals Interlayer Coupling Induces Distinct Linear Dichroism in WSe2 Photodetectors

AbstractDriven by the unique linear dichroism feature of anisotropic two‐dimensional (2D) materials, much attempt has been made to introduce artificial anisotropy into isotropic 2D materials to deliver polarization‐sensitive performance. However, those methods have not been widely promoted because of technical limitations. This paper reports on the successful modulation to the structural symmetry of WSe2 through van der Waals (vdW) interlayer coupling. Correspondingly, both the polarized Raman and photoluminescence (PL) spectra of WSe2 in heterostructure exhibit periodic variation tendency. Similarly, direction‐sensitive electronic transport has also been observed in WSe2/CrOCl heterostructure, and the conductance along armchair direction is ≈1.5 times of that along zigzag direction. As a functional illustration to the interlayer coupling induced linear dichroism, angle‐dependent photodetection is conducted to WSe2/CrOCl device. With light irradiation at 532 nm, the device photocurrent along armchair direction is 1.27 times higher than that along zigzag direction. The abnormal linear dichroism of WSe2 in the study clearly proves that few‐layer WSe2 on CrOCl flake has been entitled with artificial anisotropy. The interlayer coupling method is feasible and practical in 2D‐material range, offering the possibility to develop polarization‐dependent electronic, pyroelectric, and photoelectric devices from isotropic 2D materials.

Design of Sb2Te3 nanoblades serialized by Te nanowires for a low-temperature near-infrared photodetector.

The dangling bond on the surface of bulk materials makes it difficult for a physically contacted heterojunction to form an ideal contact. Thus, periodic epitaxial junctions based on Sb2Te3 nanoblades serialized by Te nanowires (Sb2Te3/Te) were fabricated using a one-step hydrothermal epitaxial growth method. X-ray diffraction and electron microscopy reveal that the as-prepared product has a good crystal shape and heterojunction construction, which are beneficial for a fast photoresponse due to the efficient separation of photogenerated carriers. When the Sb2Te3/Te composite is denoted as a photodetector, it shows superior light response performance. Electrical analysis showed that the photocurrent of the as-fabricated device declined with temperatures rising from 10K to 300K at 980nm. The responsivity and detectivity were 9.5 × 1011μAW-1 and 1.22 × 1011 Jones at 50K, respectively, which shows better detection performance than those of other Te-based photodetector devices. Results suggest that the as-constructed near-infrared photodetector may exhibit prospective application in low-temperature photodetector devices.

Light intensity dependence of the photocurrent in organic photovoltaic devices

The competition between recombination and extraction of carriers defines the charge collection efficiency and, therefore, the overall performance of organic photovoltaic devices, including solar cells and photodetectors. In this work, we describe different components of the steady-state light intensity-dependent photocurrent (IPC) and charge collection efficiency under operational conditions. Further, we demonstrate how different loss mechanisms can be identified based on their unique signatures in the IPC. In particular, we show how IPC can be used to distinguish first-order, trap-assisted recombination from other first-order photocurrent loss mechanisms, which dominate at the low-intensity characteristic of indoor light-harvesting applications. The theoretical framework is presented and verified by a one-dimensional drift-diffusion device model. Finally, the extended IPC methodology is validated on organic thin-film photovoltaic devices. We conclude that the relatively straightforward measurement of IPC over a large dynamic range can be a powerful tool for understanding solar and indoor device fundamentals. • IPC is a tool for understanding photovoltaic device fundamentals • Photocurrent loss mechanisms are identified based on their signatures in IPC • The theoretical framework is verified with a drift-diffusion device model • Experimental demonstration of IPC method on state-of-the-art organic solar cells Zeiske et al. present a combined theoretical and experimental study of intensity-dependent photocurrent (IPC), a tool for understanding solar and indoor device fundamentals, to identify different photovoltaic device performance-limiting photocurrent loss mechanisms based on their unique signatures in IPC.

Surface plasmon resonance enhanced self-powered graphene/Al2O3/InGaAs near-infrared photodetector

In recent years, there has been extensive research on improving the performance of photodetectors. In this paper, the performance of a graphene/Al2O3/InGaAs photodetector is studied. In order to reduce the dark current of this device and improve the photocurrent, the structure of the device is optimized to improve the responsivity of the device. A 2 nm thick Al2O3 layer is inserted as the passivation layer. The InP layer between the SiNx layer and the InGaAs layer is retained. It is speculated that the InP layer could reduce the defects and interface states between layers. A layer of silver nanoparticles (Ag NPs) was spin coated on the surface of the single-layer graphene, and the surface plasmon resonance of Ag NPs could enhance the local electric field of InGaAs interface and increase the light absorption of graphene, which can promote carrier generation and transmission in graphene and, thus, effectively enhance the photocurrent of device. The improved device achieves a high responsivity of 265.41 mA/W at 1064 nm and a detection rate of 4.06 × 1011 cm Hz1/2 W−1. At −1.25 V, the responsivity of the device is improved to 1618.8 mA/W.

Enhanced photoconductivity performance of microrod-based Sb2Se3 device

Antimony selenide is a potential material among 2D materials for photovoltaic applications due to its broad absorption range from visible to NIR. In thin-film photodetector, the formation of Sb2O3 limits the device's photocurrent and low bias operation. This work compares a Sb2Se3 microrod-based device and a thin film-based device. Because of the lower bandgap than the film-based Sb2Se3, the microrod-based device showed a broadband photoresponse in near-IR and visible regions. The photocurrent was measured at 1064 nm wavelength with variable power for the microrod-based device. The device offered a responsitivity of 0.036 mA/W and external quantum efficiency of 42 % at 1064 nm and 12 mW/cm2 power density. Also, the photocurrent increased from nano-Amps to the micro-Amps for the rod. Given the high response and low bias operation, the present device paves a path for a new device with a simple processing method.

Revealing the Variation of Photodetectivity in MAPbI3 and MAPb(I0.88Br0.12)3 Single Crystal Based Photodetectors Under Electrical Poling-Induced Polarization

The use of electrical poling to induce polarization potential has been found to increase the photocurrent (Ilight) in hybrid perovskite-based devices; however, the origin of this process has not been fully understood. Here, we study the effect of electrical poling on the photodetection properties of self-powered photodetectors (PDs) based on halide perovskites in two different phase structures (i.e., tetragonal and cubic). Specifically, extensive investigations are performed on the MAPbI3 (tetragonal) and MAPb(I0.88Br0.12)3 (cubic) single crystals (SCs). Our characterization results revealed that the Ilight has increased by 2-fold during forward poling and decreased during reverse poling in both PDs. The improved Ilight is caused by polarization induced ion migration, which builds remanent potential due to ion accumulation near metal electrodes. The effect of this polarization was found to be greater in MAPbI3 PD as compared to MAPb(I0.88Br0.12)3 PD, which influences the interface band bending and reduces Schottky barrier height (SBH). This study highlights that the modification of SBH, which describes the potential energy barrier for electrons formed at a metal–semiconductor junction, can tune the photocurrent and response time of PDs.