Showing papers on "Band offset published in 2020"
TL;DR: In this paper, the electronic, optical, and photocatalytic properties of GaSe/HfS2 heterostructures are studied via first-principles calculations.
74 citations
TL;DR: In this article, β-gallium oxide (Ga2O3) films were deposited on Si (100) substrate using pulsed laser deposition (PLD) technique in order to observe the crystallinity variation due to the annealing.
63 citations
TL;DR: In this paper, a design rule of heterojunction structure of zinc sulfide (ZnS) was proposed to improve photocatalytic performance of ZnS/NixSy.
58 citations
TL;DR: In this paper, the authors demonstrate TFETs based on BP/InSe heterojunctions with diverse electrical transport characteristics: forward rectifying, Zener-tunneling and backward rectifying characteristics are realized in BP/INSe junctions with different thickness of the BP layer or by electrostatic gating of the junction.
Abstract: Atomically thin layers of van der Waals (vdW) crystals offer an ideal material platform to realize tunnel field effect transistors (TFETs) that exploit the tunneling of charge carriers across the forbidden gap of a vdW heterojunction. This type of device requires a precise energy band alignment of the different layers of the junction to optimize the tunnel current. Amongst two-dimensional (2D) vdW materials, black phosphorus (BP) and indium selenide (InSe) have a Brillouin zone-centered conduction and valence bands, and a type II band offset, both ideally suited for band-to-band tunneling. Here, we demonstrate TFETs based on BP/InSe heterojunctions with diverse electrical transport characteristics: forward rectifying, Zener-tunneling and backward rectifying characteristics are realized in BP/InSe junctions with different thickness of the BP layer or by electrostatic gating of the junction. Electrostatic gating yields a large on/off current ratio of up to 108 and negative differential resistance at low applied voltages (V ~ 0.2V). These findings illustrate versatile functionalities of TFETs based on BP and InSe, offering opportunities for applications of these 2D materials beyond the device architectures reported in the current literature.
58 citations
TL;DR: This work introduces an inverted structure photodetector based on n-type Si and p-type PbS CQDs, which has lower energy band offset which provides higher efficient charge extraction for device.
Abstract: Silicon and PbS colloidal quantum dot heterojunction photodetectors combine the advantages of the Si device and PbS CQDs, presenting a promising strategy for infrared light detecting. However, the construction of a high-quality CQDs:Si heterojunction remains a challenge. In this work, we introduce an inverted structure photodetector based on n-type Si and p-type PbS CQDs. Compared with the existing normal structure photodetector with p-type Si and n-type PbS CQDs, it has a lower energy band offset that provides more efficient charge extraction for the device. With the help of Si wafer surface passivation and the Si doping density optimization, the device delivers a high detectivity of 1.47 × 1011 Jones at 1540 nm without working bias, achieving the best performance in Si/PbS photodetectors in this region now. This work provides a new strategy to fabricate low-cost high-performance PbS CQDs photodetectors compatible with silicon arrays.
43 citations
TL;DR: The appropriate bandgap, suitable band edge positions, and effective carrier separation make the h-BN/C2N HS a promising candidate for use as a photocatalyst in water-splitting.
Abstract: The construction of a heterostructure (HS) is an effective strategy to modulate the desired properties of two-dimensional (2D) materials and to extend their applications. In this paper, based on the density functional theory, we predict a metal-free type-II HS formed by h-BN and C2N single layers. The h-BN/C2N HS possesses a smaller bandgap than individual h-BN and C2N single layers, and it exhibits excellent visible light absorption. Importantly, its band edge positions satisfy the requirements for spontaneous water-splitting. With the assistance of the built-in electric field across the HS and the band offset, the photoinduced carriers can be readily spatially separated. Free energy calculations indicate the high catalytic activity for water oxidation and reduction reactions. The performance can be further enhanced by strain, which modulates the bandgap and the band edge positions of the HS. The band alignment may undergo a transition from type-I to type-II under strain, offering an effective switch for the reaction. The appropriate bandgap, suitable band edge positions, and effective carrier separation make the h-BN/C2N HS a promising candidate for use as a photocatalyst in water-splitting.
38 citations
TL;DR: The results not only provide a theoretical design, but also reveal the fundamental separation mechanism of the photo-generated carriers in the BlueP/C2N heterojunction, which greatly extended the area of light adsorption to the visible light region.
Abstract: An appropriate band structure and effective carrier separation are very important for the performance of a solar photocatalyst. In this paper, based on first-principles calculations, it was predicted that blue phosphorene (BlueP) and a C2N monolayer can form a promising metal-free type-II heterojunction. The electronic structure of the BlueP/C2N heterojunction facilitated the overall water splitting reactions well. The projected band structure showed that the conduction band edge was contributed by C2N and the valence band edge was dominated by BlueP. Under the combination of the driving force of the band offset and the built-in electric field between the two layers, the photo-generated electrons and holes were transferred spontaneously to the conduction band of C2N and the valence band of BlueP, respectively. An effective carrier separation in the heterostructure was thus achieved. More notably, the obtained light absorption of the BlueP/C2N junction showed an obvious red-shift, which greatly extended the area of light adsorption to the visible light region. We further proposed that strain could also be used to modulate the band gap and the band edge positions of the heterojunction. Our results not only provide a theoretical design, but also reveal the fundamental separation mechanism of the photo-generated carriers in the BlueP/C2N heterojunction.
38 citations
TL;DR: In this article, the authors theoretically demonstrate that the 2D GaSe/GeS van der Waals (vdW) heterobilayer is a robust type-II band alignment semiconductor with a direct band gap of 1.8 eV.
Abstract: Constructing two dimensional (2D) van der Waals (vdW) heterostructures and understanding their electronic properties are pivotal for developing novel electronic devices. In this work, by using the first-principles calculations, we theoretically demonstrate that the 2D GaSe/GeS van der Waals (vdW) heterobilayer is a robust type-II band alignment semiconductor with a direct band gap of 1.8 eV. It exhibits a remarkable absorbance coefficient of ∼105 cm−1 from the UV to visible light region and a high carrier mobility with anisotropic character. The photoelectric conversion efficiency (PCE) shows a tremendous enhancement under external strain, and shows an efficiency of up to ∼16.8% at 2% compressive strain. Besides, we find that applying an external electric field can effectively modulate its band gap and band offset. Interestingly, a larger external electric field can induce nearly free electron (NFE) states around the conduction band minimum (CBM) in the GaSe/GeS heterobilayer, which leads to the band transition from a semiconductor to metallic status. These results indicate that 2D GaSe/GeS heterostructures will have widespread application prospects in future photovoltaic and optoelectric nanodevices.
34 citations
TL;DR: In this article, a hydrogen-terminated diamond (H-diamond) metal-oxide-semiconductor field effect transistors (MOSFETs) were fabricated on a polycrystalline diamond substrate.
Abstract: Hydrogen-terminated diamond (H-diamond) metal-oxide-semiconductor field effect transistors (MOSFETs) were fabricated on a polycrystalline diamond substrate. The device has a gate length of 2 μm and uses Al2O3 grown by atomic layer deposition at 300 °C as a gate dielectric and passivation layer. The Al2O3/H-diamond interfacial band configuration was investigated by X-ray photoelectron spectroscopy, and a large valence band offset (3.28 eV) that is very suitable for p-channel H-diamond FETs was observed. Meanwhile, the measured O/Al ratio hints that there are Oi or VAl defects in the Al2O3 dielectric, which can work as an acceptorlike transfer doping material on a H-diamond surface. The device delivers the maximum saturation drain current of over 200 mA/mm, which is the highest for 2-μm H-diamond MOSFETs with the gate dielectric or passivation layer grown at 300 °C or higher temperature. The ultrahigh on/off ratio of 1010 and ultralow gate leakage current of below 10−12 A have been achieved. The high device performance is ascribed to the ultrahigh carrier density, good interface characteristics, and device processes. In addition, the transient drain current response of the device can follow the gate voltage switching on/off pulse at a frequency from 100 kHz to 1 MHz, which indicates the potential of the H-diamond FETs in power switch applications.
33 citations
TL;DR: In this paper, the electronic and optical properties of GaS/g-C3N4 van der Waals (vdWs) heterostructures were studied using density functional theory based on first-principles.
29 citations
TL;DR: In this paper, the effect of conduction band offset (CBO), VBO and interface defect density (Nt) on the performance of perovskite solar cells (PSCs) for spiro-MeOTAD as organic HTM and its detailed comparison is made with Cu-based inorganic HTMs to get better insight about the best inorganic HPM.
TL;DR: In this paper, NiO-decorated titanium dioxide (TiO2) heterojunction photodetectors were prepared by two-step anodization, which showed high values of responsivity (86 A/W), external quantum efficiency (292%), and detectivity (2.2
Abstract: Nickel oxide (NiO)-decorated titanium dioxide (TiO2) heterojunction photodetectors were prepared by two-step anodization. Surface scattering of NiO particles was successfully controlled by varying second-step anodizing voltage, with substantially less clustering of NiO particles on the TiO2 nanotubes (NTs) observed as the voltage increased. Fabricated photodetectors exhibited higher sensitivity to UV light as NiO surface dispersion increased. Electronic bandgap of TiO2 and that of NiO was determined as ~ 3.35 eV and ~ 3.80 eV, respectively. Introduction of NiO particles on well-ordered TiO2 NTs narrowed the bandgap of TiO2, and the difference between work functions of TiO2 and NiO produced sufficient built-in electric field to separate the electron–hole pairs. This led to an enhanced performance of NiO/TiO2 heterojunction photodetectors, which showed high values of responsivity (86 A/W), external quantum efficiency (292%), and detectivity (2.2 × 1010 Jones) under 365 nm UV light illumination. The valence and conduction band offsets at the interface of the NiO/TiO2 heterojunction were determined as ~ 1.54 eV and ~ 1.99 eV, respectively.
TL;DR: An Nb-doped TiO2 (Nb-TiO2) film comprising a double structure stacked with a bottom compact layer and top mesoporous layers was synthesized by treating a treating a Ti precursor-coated substrate using a one-step low-temperature steam-annealing (SA) method to reduce the bandgap of perovskite.
Abstract: An Nb-doped TiO2 (Nb-TiO2) film comprising a double structure stacked with a bottom compact layer and top mesoporous layers was synthesized by treating a Ti precursor-coated substrate using a one-step low-temperature steam-annealing (SA) method. The SA-based Nb-TiO2 films possess high crystallinity and conductivity, and that allows better control over the conduction band (CB) of TiO2 for the electron transport layer (ETL) of the perovskite solar cells by the Nb doping level. Optimization of power conversion efficiency (PCE) for the Nb-TiO2-based ETL was combined with the CB level tuning of the mixed-halide perovskite by changing the Br/I ratio. This band offset management enabled to establish the most suitable energy levels between the ETL and the perovskites. This method was applied to reduce the band gap of perovskites to enhance the photocurrent density while maintaining a high open-circuit voltage. As a result, the optimal combination of 5 mol % Nb-TiO2 ETL and 10 mol % Br in the mixed-halide perovskite exhibited high photovoltaic performance for low-temperature device fabrication, achieving a high-yield PCE of 21.3%.
TL;DR: It is demonstrated that the resistance of large area MoS2 and MoSe2 thin film, prepared via low pressure chalcogenation of molybdenum film, decreases by up to two orders of magnitude upon doping using benzyl viologen (BV) molecule.
Abstract: Scalable heterojunctions based on two-dimensional transitional metal dichalcogenides are of great importance for their applications in the next generation of electronic and optoelectronic devices. However, reliable techniques for the fabrication of such heterojunctions are still at its infancy. Here we demonstrate a simple technique for the scalable fabrication of lateral heterojunctions via selective chemical doping of TMD thin films. We demonstrate that the resistance of large area MoS2 and MoSe2 thin film, prepared via low pressure chalcogenation of molybdenum film, decreases by up to two orders of magnitude upon doping using benzyl viologen (BV) molecule. X-ray photoelectron spectroscopy (XPS) measurements confirms n-doping of the films by BV molecules. Since thin films of MoS2 and MoSe2 are typically more resistive than their exfoliated and co-evaporation based CVD counterparts, the decrease in resistance by BV doping represents a significant step in the utilization of these samples in electronic devices. Using selective BV doping, we simultaneously fabricated many lateral heterojunctions in 1 cm2 MoS2 and 1 cm2 MoSe2 films. The electrical transport measurements performed across the heterojunctions exhibit current rectification behavior due to a band offset created between the doped and undoped regions of the material. Almost 84% of the fabricated devices showed rectification behavior demonstrating the scalability of this technique.
TL;DR: In this article, a self-driven 3D/2D CZTS/MoS2 heterojunction broadband photodetector was constructed with high responsivity 141 mAh/W, outstanding photoswitching capability (IOn/IOff) and fast response (τr/τd/= ǫ81/79 ms).
TL;DR: In this article, first-principles density-functional theory calculations were carried out to explore the surface energies and electronic properties of hematite surface slabs and polar Fe2O3 surfaces, examining several competing terminations of the α-Fe 2O3 (0001) surface modeled via slabs with increasing surface area from 12 Fe (21.983 A2) to 48 Fe-atom (87.92 A2).
TL;DR: Buyukcakir et al. as mentioned in this paper predicted a quinazoline based covalent organic framework (Q-COF), which has been synthesized recently (O. Chem., Int. Ed., 2019, 58, 872-876), as an excellent 2D photovoltaic material.
Abstract: Great efforts have been made in exploring two-dimensional (2D) semiconductors with appropriate band gaps and high optical absorption for their great potential applications in solar cells. Here, by using density-functional theory calculations, we predicted a quinazoline based covalent organic framework (Q-COF), which has been synthesized recently (O. Buyukcakir, et al., Angew. Chem., Int. Ed., 2019, 58, 872–876), as an excellent 2D photovoltaic material. We reveal that a Q-COF monolayer, which can be exfoliated feasibly from its layered bulk, possesses a desired direct band-gap of 1.18 eV, and exhibits promising optical absorption (105 cm−1) in the visible and near-infrared light region. Moreover, we found that Q-COF and ZnSe monolayers could form a heterojunction with a type-II band alignment, using which a photoelectric conversion efficiency (PCE) of 16.89% can be reached. Under strain engineering, the band gap and the band offset of the Q-COF/ZnSe heterojunction can be effectively tuned, and the PCE can be further improved to 22.32%. Our results would motivate more experimental and theoretical research to further explore the potential applications of the Q-COF monolayer in optoelectronic devices, especially in solar cells.
22 Jun 2020
TL;DR: Ultrafast spectroscopy reveals a longer lifetime and efficient separation of photoexcited charge carriers in Cu2CdSnS4 (CCTS) nanocrystals compared to that of CZTS and points toward efficient separation across the p–n junction in the ultrafast time scale and highlight a route to improve device performances.
Abstract: To improve the constraints of kesterite Cu2ZnSnS4 (CZTS) solar cell, such as undesirable band alignment at p–n interfaces, bandgap tuning, and fast carrier recombination, cadmium (Cd) is introduced into CZTS nanocrystals forming Cu2Zn1–xCdxSnS4 through cost-effective solution-based method without postannealing or sulfurization treatments. A synergetic experimental–theoretical approach was employed to characterize and assess the optoelectronic properties of Cu2Zn1–xCdxSnS4 materials. Tunable direct band gap energy ranging from 1.51 to 1.03 eV with high absorption coefficient was demonstrated for the Cu2Zn1–xCdxSnS4 nanocrystals with changing Zn/Cd ratio. Such bandgap engineering in Cu2Zn1–xCdxSnS4 helps in effective carrier separation at interface. Ultrafast spectroscopy reveals a longer lifetime and efficient separation of photoexcited charge carriers in Cu2CdSnS4 (CCTS) nanocrystals compared to that of CZTS. We found that there exists a type-II staggered band alignment at the CZTS (CCTS)/CdS interface, from cyclic voltammetric (CV) measurements, corroborated by first-principles density functional theory (DFT) calculations, predicting smaller conduction band offset (CBO) at the CCTS/CdS interface as compared to the CZTS/CdS interface. These results point toward efficient separation of photoexcited carriers across the p–n junction in the ultrafast time scale and highlight a route to improve device performances.
TL;DR: In this article, a novel structure is proposed for the efficiency enhancement of experimentally designed Sb 2 Se 3 solar cell by device optimization, the band offset engineering, and Hole Transport Layer (HTL) with the aid of numerical modeling in SCAPS-1D simulator.
TL;DR: In this article, the authors reported that a very controlled oxidation occurs in the MoS2 colloidal QDs under the ambient condition giving rise to oxide/MoS2 core-shell structure.
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TL;DR: In this paper, the authors demonstrate TFETs based on BP/InSe heterojunctions with diverse electrical transport characteristics: forward rectifying, Zener-tunneling and backward rectifying characteristics are realized in BP/INSe junctions with different thickness of the BP layer or by electrostatic gating of the junction.
Abstract: Atomically thin layers of van der Waals (vdW) crystals offer an ideal material platform to realize tunnel field effect transistors (TFETs) that exploit the tunneling of charge carriers across the forbidden gap of a vdW heterojunction. This type of device requires a precise energy band alignment of the different layers of the junction to optimize the tunnel current. Amongst two-dimensional (2D) vdW materials, black phosphorus (BP) and indium selenide (InSe) have a Brillouin zone-centered conduction and valence bands, and a type II band offset, both ideally suited for band-to-band tunneling. Here, we demonstrate TFETs based on BP/InSe heterojunctions with diverse electrical transport characteristics: forward rectifying, Zener-tunneling and backward rectifying characteristics are realized in BP/InSe junctions with different thickness of the BP layer or by electrostatic gating of the junction. Electrostatic gating yields a large on/off current ratio of up to 108 and negative differential resistance at low applied voltages (V ~ 0.2V). These findings illustrate versatile functionalities of TFETs based on BP and InSe, offering opportunities for applications of these 2D materials beyond the device architectures reported in the current literature.
TL;DR: This work investigates the impact of interlayer coupling on the SHG response across the A- and B-exciton resonances in the MoS2 homo-BLs and develops an approach for fully exploiting the TMDC VHs for highly efficient broadband SHG applications.
Abstract: Noncentrosymmetric monolayers (MLs) of transitional metal dichalcogenides (TMDCs) and their 3R-type vertical stacks provide an ideal platform for studying atomic-scale nonlinear light-matter...
TL;DR: The bottom-up on-surface synthesis of 1D and 2D monolayer carbon nitride nanostructures with precise control of the nitrogen-atom doping sites and pore sizes is demonstrated and offers direct atomic-level insights into the local electronic structure of the heteroatom-doped carbon-based materials.
Abstract: Heteroatom-doped carbon-based materials are of significance for clean energy conversion and storage due to its fascinating electronic properties, low cost, high durability and environmental-friendl...
TL;DR: In this paper, the authors report the band discontinuities at the MoS2/III-nitride (InN, GaN, and AlN) heterointerfaces.
Abstract: Heterojunction band offset parameters are critical for designing and fabricating junction-based devices as these parameters play a crucial role in determining the optical and electronic properties of a device. Herein, we report the band discontinuities at the MoS2/III-nitride (InN, GaN, and AlN) heterointerfaces. Few-layer MoS2 thin films are deposited by pulsed laser deposition on III-nitrides/c-sapphire substrates. Band offsets [valence band offset (VBO) and conduction band offset (CBO)] at the heterojunctions are determined by high-resolution x-ray photoelectron spectroscopy. The estimated band alignments are found to be type-I (VBO: 2.34 eV, CBO: 2.59 eV), type-II (VBO: 2.38 eV, CBO: 0.32 eV), and type-III (VBO: 2.23 eV, CBO: 2.87 eV) for MoS2/AlN, MoS2/GaN, and MoS2/InN, respectively. Such determination of the band offsets of 2D/3D heterojunctions paves a way to understand and design the futuristic photonic and electronic devices using these material systems.
TL;DR: In this article, the electronic properties of BAs/MoSe2 van der Waals heterostructures have been investigated through first-principles calculations and the effects of the biaxial strains and electric field are also considered for electronic properties.
Abstract: The electronic properties of BAs/MoSe2 van der Waals heterostructures have been investigated through first-principles calculations. Different structural configurations of BAs/MoSe2 heterostructures are compared with binding energy and the stability is proved by calculating the phonon spectrum. The stable BAs/MoSe2 heterostructure has a direct band gap and displays a type-Ⅰ band alignment. The effects of the biaxial strains and electric field are also considered for electronic properties. Both biaxial strains and vertical electric field are able to tune the values of band gaps and band offset. Meanwhile, BAs/MoSe2 van der Waals heterostructures exhibit tunable band alignments between type-Ⅰ and type-Ⅱ by strains or electric field. Type-Ⅱ van der Waals heterostructures own an interesting perspective in photocatalysis. Our results provide a potential way to realize the tunable electronic properties of BAs/MoSe2 van der Waals heterostructures.
TL;DR: The results show that Janus MXY monolayer has an intrinsic dipole moment and a direct band gap, however, for MXY bilayers strong interlayer coupling will cause direct to indirect band gap transition, and the existence of the dipole Moment leads to a significantly large interlayer band offset, being the driving force for the formation of interlayer excitons.
Abstract: Based on the first-principles calculations, we studied the intrinsic dipole moment and electronic properties of Janus MXY (M = Mo, W; X ≠ Y = S, Se) monolayers, bilayers and heterostructures with graphene, and the possibility of MXY encapsulating graphene. The results show that Janus MXY monolayer has an intrinsic dipole moment and a direct band gap. However, for MXY bilayers strong interlayer coupling will cause direct to indirect band gap transition, and the existence of the dipole moment leads to a significantly large interlayer band offset, being the driving force for the formation of interlayer excitons. In MXY/graphene heterostructures, changes in the direction of intrinsic dipole moment will cause a change in Schottky barrier height and even the transition between p- and n-type Schottky contacts. Independent of the interface atomic layer of Janus MXY, on one hand, the Dirac cone still exists in graphene, proving that MXY is an ideal coating material. On the other hand, the type-II band alignment will disappear as the intrinsic dipole moment disappears, confirming that the intrinsic dipole moment plays a vital role in the formation of a large band offset. Our results provide guidance for the study of interlayer excitonic states, the experimental construction of atomically thin p-n junctions and the encapsulation of graphene.
TL;DR: It is found that while the ET rate from TMDCs (MoS2 and WSe2) to fullerenes is relative insensitive to the band offset, the ET rates can be reduced by an order of magnitude when the bandoffset is large.
Abstract: Excited-state electron transfer (ET) across molecules/transition metal dichalcogenide crystal (TMDC) interfaces is a critical process for the functioning of various organic/TMDC hybrid optoelectronic devices. Therefore, it is important to understand the fundamental factors that can facilitate or limit the ET rate. Here it is found that an undesirable combination of the interfacial band offset and the spatial dimensionality of the delocalized electron wave function can significantly slow down the ET process. Specifically, it is found that whereas the ET rate from TMDCs (MoS2 and WSe2) to fullerenes is relative insensitive to the band offset, the ET rate from TMDCs to perylene molecules can be reduced by an order of magnitude when the band offset is large. For the perylene crystal, the sensitivity of the ET rate on the band offset is explained by the 1D nature of the electronic wave function, which limits the availability of states with the appropriate energy to accept the electron.
TL;DR: In this paper, the electronic and optical properties of novel two-dimensional van der Waals heterostructures constituted by ternary BCxN (x = 0, 2, and 6) and black phosphorene (BlackP) were investigated.
TL;DR: In this paper, the authors investigated the electronic transport properties, photocatalytic reaction mechanism and optical properties of novel g-C6N6/GaS heterojunction.
TL;DR: The calculated band offset (BOs) for 1I-BiOI/TiO2 heterojunction indicates that the interfacial structure contributes a lot to a suitable band alignment which can disperse the photo-generated carriers into the opposite sides of the interface, so this could effectively weaken the electron-hole recombination.
Abstract: Using the first-principle calculation that is based on the density functional theory (DFT), our group gains some insights of the structural, electronic and optical properties of two brand new types of BiOI/TiO2 heterojunctions: 1I-terminated BiOI {001} surface/TiO2 (1I-BiOI/TiO2) and BiO-terminated BiOI {001} surface/TiO2 (BiO-BiOI/TiO2). The calculation illustrates that BiOI/TiO2 heterojunction has excellent mechanical stability, and it shows that there is a great possibility for the BiOI/TiO2 heterojunction to be used in visible-light range, hence the photocatalytic ability can be enhanced dramatically. Especially, from the calculation, we discovered that there are two specific properties: the band-gap of 1I-BiOI/TiO2 heterojunction reduces to 0.28 eV, and the BiO-BiOI/TiO2 semiconductor material changes to n-type. The calculated band offset (BOs) for 1I-BiOI/TiO2 heterojunction indicates that the interfacial structure contributes a lot to a suitable band alignment which can disperse the photo-generated carriers into the opposite sides of the interface, so this could effectively weaken the electron-hole recombination. Meanwhile, the built-in potential around the interface accelerates the movement of the photo-generated electron-hole pairs. We believe this is the reason that the BiOI/TiO2 material shows perfect photocatalytic performance. This paper can provide theoretical support for the related research, especially the further research of the BiOI-based material.