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A two-dimensional ferromagnetic layer with a large Curie temperature is highly desired for spintronics applications.

The 2D MoTe2/VSe2 heterostructure shows a large ANC of 2.3 A K−1 m−1 when the electric field was applied from the VSe2 to MoTe2 layers and switches to −0.6 A K−1 m−1 with an opposite electric field.

Two-dimensional alloy systems can show the possibility for thermoelectric applications because of their low thermal conductivity due to the complex structural effect. Therefore, we investigated the thermoelectric (TE) performance of the GaSe0.5Te0.5 alloy monolayer. We found a direct band gap of 2.19 eV by using the HSE06 hybrid functional including the spin–orbit coupling (SOC) effect. Based on this band structure, we explored the TE properties of both n- and p-type systems. The n-type system showed better TE performance than the p-type system. For instance, the n-type maximum ZT was 2.05 at 700 K, and this high ZT had weak carrier concentration dependence. For instance, it was changed by only ∼10% in the range of carrier concentrations of 1–10 × 1019 electrons per cm3. Moreover, we also observed that the n-type GaSe0.5Te0.5 alloy showed better TE performance compared with the ZTs found in pure GaSe and GaTe monolayers. Overall, we proposed that the n-type GaSe0.5Te0.5 alloy shows outstanding thermoelectric performance, and this result will provoke further experimental investigations to verify our prediction.

The study on two-dimensional (2D) magnetic materials attracts extensive research interest. Nonetheless, it is rare to find reports on heterostructures. Thus, we investigated the magnetic properties...

Using the first principles calculations, we explored the optical properties of the two-dimensional α-GeTe structure. The 2D monolayer α-GeTe had an indirect band gap of 1.79 eV, and that indirect band gap was still observed in the bilayer although the band gap had decreased to 0.61 eV. We found that the optical band gap was much larger than the electrical band gap, which was due to the indirect band gap feature of the 2D α-GeTe system. In both systems, we found a very large refractive index in the visible range. Particularly, the bilayer system had a refractive index larger than 2.5 for blue light. Furthermore, the bilayer structure was found to have a larger reflectivity at ultraviolet frequencies. Consequently, we propose that the bilayer α-GeTe film can be utilized for potential optical device applications.

Using the first principle calculations, we investigated the temperature-dependent magnetic properties of Bi-doped Fe16N2. We found that the Bi doping resulted in the lattice expansion and consequently the volume expansion occurred. Due to this volume expansion, the saturation magnetization of Bi-doped system was suppressed by 12% compared with that of pure Fe16N2. Nonetheless, the hybridization effect between Fe 3d and Bi 6p orbitals contributed to enhancing the magnetocrystalline anisotropy from 0.73 meV/cell in pure Fe16N2 to 1.57 meV/cell in Bi-doped system. Through the temperature-dependent magnetization dynamics, we found that the Bi-doped system had a coercive field of 9.63 kOe at 300 K while the pure Fe16N2 alloy had a coercive field of 3.61 kOe. Furthermore, a maximum energy product of 70.2 MGOe at 300 K was found in Bi-doped system. Overall, we propose that the Bi-doped system can be a potential rare-earth-free permanent magnet (PM).

Magnetic proximity effect can be used to tailor the magnetic ground state and valley polarization in the monolayer of transition metal dichalcogenides. Thus, we explore the effect of biaxial tensile and compressive strain on valley polarization in the WSe

Motivated by the recent fabrication of the hexagonal PdTe2 monolayer, we investigated the thermoelectric properties of the hexagonal and pentagonal PdTe2 structures using two approaches. The pentagonal monolayer has not been synthesized yet. The hexagonal layer had an indirect band gap of 0.17 eV while the pentagonal structure had an indirect band gap of 1.18 eV. By applying the semiempirical Wiedemann-Franz law to calculate the electronic thermal conductivity, we found that both hexagonal and pentagonal structures had a very high ZT, more than 3. However, the Wiedemann-Franz law underestimated the electronic thermal conductivity, and this resulted in a high ZT. Thus, we employed the Boltzmann transport equation for the electronic thermal conductivity. At high temperature (>500 K), the pentagonal PdTe2 structure showed a better thermoelectric performance than the hexagonal structure. However, both structures displayed the same ZT of 0.8 at 300 K. We propose that the hexagonal PdTe2 can be a potential high performance thermoelectric material at room temperature.

Using the electronic band structure of the optimized monolayer and bilayer As 1-xPx structure calculated through the DFT calculation a comprehensive study on the electronic transport properties based on the Boltzmann transport theory are investigated within the respect of the constant relaxation time approximation τ. The Seebeck coefficient of the monolayer As xP1-x system has a larger value than the bilayer system and shows no anisotropic behavior along the armchair and zigzag directions while we found a higher electrical conductivity along the armchair direction in both mono and bilayer structures. A similar behavior was found in the electronic contribution to the thermal conductivity and this was understood from the Weidmann–Franz law. We also found that the power factor had a larger value along the armchair direction than the zigzag direction. Besides, in monolayer system, the p-type As 0.75P0.25 alloy showed a highest power factor while the n-type bilayer As0.75P0.25 alloy system displayed a highest power factor. Thus, we suggest that the thermoelectric property can be improved in alloy system compared with the pristine phosphorene and arsenene layer.

Using the full potential linearized augmented plane wave method, we explored the magnetocrystalline anisotropy of Dy impurity doped α″-Fe16N2. Here, we considered two different Dy concentrations (1.56 and 3.125%). We also investigated the temperature dependence of the magnetic properties. The Dy site occupancy was found to be concentration dependent. The magnetic moments of Fe atoms near the Dy impurity was suppressed. However, we found a large magnetic moment in Dy atom (4.85–4.87 μB). Compared with the magnetic anisotropy constant in the pristine α″-Fe16N2 (0.57 MJ/m3), we obtained an enhanced perpendicular magnetic anisotropy. The calculated anisotropy constants in 1.56% Dy doping was 0.97 MJ/m3 while it became 1.27 MJ/m3 in 3.125% Dy doping. The Curie temperature in the pristine structure was about 820 K and it was suppressed to 765 K and 605 K in 1.56% and 3.125% Dy doping. At room temperature (300 K), the coercive field of 3.125% Dy doped system was enhanced almost 50% compared with that of the pure Fe16N2. We also found a maximum energy product of 50.9 MGOe for 3.125% Dy doping at 300 K. Our finding may suggest that the α″-Fe16N2 can be a potential permanent magnet with a lean Dy doping.

Using the density functional theory and non-equilibrium Green's function method, we investigated the bias dependent transport property of point defective hydrogen passivated tilted phosphorene nanoribbons . Here, we calculated the I-V curve by changing the defect position. Here, three different defect sites were considered; edge, central defect, and mid-point defect between edge and central region. It was found that the I-V characteristic was substantially sensitive to the defect position because the onset bias voltage and the increment in the current with bias were different from each other. Besides, unlike the conventional belief, we obtained that the magnitude of the current due to the point defect was four to five times enhanced compared with that in the defect-free pristine nanoribbon structure. We found that the simple analysis based on the Fermi level shifting at finite bias was not enough to explain the I-V curve. Instead, we realized that it was necessary to consider both bias dependent transmission coefficient and density of states in the scattering region to explain the I-V curve.

Achieving and controlling valley splitting is a core issue for valleytronics applications. Conventionally, valley splitting was achieved by applying an external magnetic field or structural manipulation. However, this approach is less efficient. Here, we explored single layer and bilayer graphene on CrI3 (g-CrI3 and 2g-CrI3) heterostructures to induce valley splitting. In g-CrI3, we found a valley splitting with the majority gap difference of Δ1↑ − Δ2↑ = 44 meV. Even in 2g-CrI3 system, we also found valley splitting of Δ1↑ − Δ2↑ = 21 meV. Moreover, we also investigated the electric field effect on valley splitting. In both systems, we observed that valley splitting could be switched in the majority spin band. For instance, the sign of gap difference at ±K changed from Δ1↑ > Δ2↑ at zero field to Δ1↑

We present the thermoelectric transport properties of Cl-doped Cu2Se1−xClx (x = 0–0.08) compounds prepared by spark plasma sintering. Cl-doping resulted in a decrease in the electrical conductivity and an increase in the Seebeck coefficient of the compound due to the donor role of Cl. Furthermore, the incorporation of Cl caused the formation of a secondary CuCl phase, which affected the structural, electrical, and thermal properties of the compounds significantly. Although the melting of CuCl limited the operating temperature to ∼ 620 K, the Cl-doped compounds exhibited significantly reduced lattice thermal conductivity because of the presence of the CuCl secondary phase. The highest ZT of 0.6 at 620 K was achieved in Cu2Se0.92Cl0.08, and the effects of CuCl on the thermoelectric transport properties of Cl-doped Cu2Se1−xClx compounds are discussed in detail.

Using the first principles calculations, we investigated the physical properties of hydrogenated black phosphorene layer. For a single H adsorption, the P top site became the most stable adsorption position and this impurity adsorption created a broken P P bond. Due to this broken bond, the adsorption of a single hydrogen atom on a phosphorene layer induced a total magnetic moment at about 1.0 μB and that the spin-polarized state was mainly localized around the dangling phosphorus atom. In the hydrogenated system, the hydrogen atoms preferred the different sublattice adsorption at rather short H H inter-atomic distance (∼3.5 A) while the sublattice dependent formation energy was greatly suppressed at larger than H H distance of 3.5 A. We obtained that the hydrogenated phosphorene layer displayed an antiferromagnetic state until the H H inter-atomic distance became around 8 A and the energy difference between ferromagnetic (FM) and antiferromagnetic (AFM) states almost vanished beyond this interatomic distance. This result may suggest that the hydrogenated phosphorene layer system shows an antiferromagnetic state at high H concentration while the exchange coupling is greatly suppressed at low H concentration. Thus, it will be possible to manipulate the magnetic property by applying even small magnetic field at low H concentration and this can feature can be utilized for spintronics applications.

Nd2Fe14B and Nd2 − xDyxFe14B (x = 0.25,0.50) particles were prepared by the modified co-precipitation followed by reduction-diffusion process. Bright field scanning transmission electron microscope (BF-STEM) image revealed the formation of Nd-Fe-B trigonal prisms in [-101] viewing zone axis, confirming the formation of Nd2Fe14B/Nd2 − xDyxFe14B. Accurate site for the Dy substitution in Nd2Fe14B crystal structure was determined as “f” site by using high-angle annular dark field scanning transmission electron microscope (HAADF-STEM). It was found that all the “g” sites are occupied by the Nd, where’s and Dy occupied only the “f” site. Anti-ferromagnetic coupling at “f” site decreased the magnetic moment values for Nd1.75Dy0.25Fe14B (23.48 µB) and Nd1.5Dy0.5Fe14B (21.03 µB) as compared to Nd2Fe14B (25.50 µB). Reduction of magnetic moment increased the squareness ratio, coercivity and energy product. Analysis of magnetic anisotropy at constant magnetic field confirmed that “f” site substitution did not change the patterns of the anisotropy. Furthermore, magnetic moment of Nd2Fe14B, Nd2 − xDyxFe14B, Nd (“f” site), Nd (“g” site) and Dy (“f” site) was recorded for all angles between 0-180o.

Valleytronics is receiving extensive research efforts. Thus, we investigated the electric field-induced valley polarization in the WSe2/CrSnSe3 heterostructures by varying the stacking order. The heterostructure shows indirect band gaps of 270 and 330 meV in the two most stable structures. The WSe2/CrSnSe3 heterostructure displays a ferromagnetic ground state with out-of-plane anisotropy (0.02 meV) in one stable stacking (S-1) while a small in-plane anisotropy (−0.01 meV) is found in other stacking (S-2). The Curie temperature is slightly enhanced to 73 K compared to the monolayer CrSnSe3. We have found the valley splitting of 4 meV in S-1 whereas it became 9 meV in the S-2 system. The valley splitting is further enhanced if an electric field is applied from CrSnSe3 to the WSe2 layer whereas it is suppressed in the reversed electric field. Particularly, the S-2 structure shows a giant valley splitting of 67 meV at an electric field of 0.6 V Å−1. We attribute this electric field-dependency to the dipolar effect. Overall, we propose that the WSe2/CrSnSe3 heterostructure can be a potential structure for obtaining a giant valley splitting.

Among the group-III chalcogenides, the two-dimensional (2D) GaSe and GaTe materials have been synthesized, but recent theoretical studies have raised controversial results regarding their thermoelectric (TE) properties. Hereby, systematically investigated the temperature and carrier concentration dependent TE properties of 2D GaSe and GaTe. We found that the GaSe had an indirect band gap of 2.94 eV while the GaTe had an indirect band gap of 1.88 eV. Both materials had almost the same Seebeck coefficients, but the p-type GaTe had the longest carrier relaxation time. We obtained the largest electrical conductivity over the thermal conductivity ratio in p-type GaTe compared with all other systems. This results in a very high p-type ZT of 0.91. Moreover, this high ZT performance is only changed by approximately 7% in a wide range of temperatures (300–700 K) and carrier concentration (1011–1013 hole cm−2). Compared with previously reported results, we find that it is necessary to consider the carrier relaxation time and spin–orbit coupling effect for determining reliable TE property. Overall, we propose that the p-type GaTe have outstanding TE property, and it can be utilized for potential TE device applications.

Valleytronics in 2D transition metal dichalcogenides (TMDs) has received extensive interest as a promising field for information processing, storage, and logic operation applications. Here, we have investigated the electric field dependent valley polarization of 2D WSe

Spin Seebeck effect (SSE) is a key factor in the spin caloritronics field, and extensive studies have been performed for potential spin thermoelectric modulator device applications. However, the performance of spin current generation was not high enough, and this is due to the weak yield of the SSE. Despite the many studies for the SSE in bulk materials, no reports are available yet in the pure two-dimensional (2D) ferromagnetic material. Hereby, we investigated the SSE of two-dimensional ferromagnetic CrI

Low lattice thermal conductivity is one of the most important physical quantities for phononic device applications. Thus, we investigated the in-plane lattice thermal conductivity of mono- and bi-layer α-GeTe systems. The lattice thermal conductivity of the monolayer system along the zigzag direction was 0.43 (W mK-1) while it was 0.21 (W mK-1) along the armchair direction at 300 K, and the lattice thermal conductivity mostly originated from the out-of-plane acoustic mode. In the bilayer system, it was significantly suppressed to 0.044 (W mK-1) and 0.047 (W mK-1) along the zigzag and armchair directions, respectively, at 300 K. Particularly, the out-of-plane acoustic mode in the bilayer had a tremendous Gruneisen parameter and this led to an ultralow in-plane lattice thermal conductivity in the bilayer, and the optical mode dominated the contribution to the lattice thermal conductivity. Our findings may raise intriguing issues regarding the thermoelectric effect, heat insulators, and phononic device applications, and stimulate further experimental studies to verify our theoretical predictions.

Recently, it was reported that the VI

Removing valley degeneracy is a necessary condition for manipulating valley degrees of freedom and storing information in future spintronics. Magnetic proximity effect has been demonstrated to be an effective way to introduce exchange interactions, especially in the case of two-dimensional (2D) van der Waals (vdW) heterostructures. We have explored the electronic properties and the valley physics of 2D ${\mathrm{WSe}}_{2}/{\mathrm{CrI}}_{3}$ using first-principles calculations. Our results show that a valley splitting of 2 meV is achieved in ${\mathrm{WSe}}_{2}/{\mathrm{CrI}}_{3}$ heterostructures thanks to the coexistence of inversion and time-reversal symmetry breaking. This value corresponds to an effective magnetic field of \ensuremath{\sim}10 T in experiments. Moreover, we demonstrate that the valley splitting is a robust feature regardless of the stacking configuration and the thickness of ${\mathrm{CrI}}_{3}$. Most importantly, by reversing the magnetization in the ${\mathrm{CrI}}_{3}$ layer, the valley splitting and polarization at ${K}^{+}$ and ${K}^{\ensuremath{-}}$ points are completely switchable. Our findings provide fundamental insights into the magnetoelectric spin-orbit coupling based spintronics applications of 2D vdW heterostructures.

One of the major obstacles for Cr-based 2D materials such as CrI

Using first principles calculations, we investigated the possibility of selecting multiple toxic gases using one substrate material. Here, we explored the transport property of H

Using the first principles method, we investigated the interface effect on the electronic structure and the magnetic properties of multilayer Fe16N2/Ag/Fe16N2 and Fe16N2/Au/Fe16N2. The thicknesses of Ag (100) and Au (100) were fixed to three monolayers, and the lattice mismatch was about 1%. The magnetic moment of Fe atoms at the interface was suppressed due to hybridization with non-magnetic Ag and Au atoms. Due to this reduction in the magnetic moments and also because of the non-magnetic volume of the Ag and Au layer, an overall 40% suppression of the magnetization was found in both systems. The hybridization between interface Ag (Au) and Fe atoms and the spin-orbit coupling associated with Ag (Au) atoms mainly contributed to the enhancement of the magnetocrystalline anisotropy. The magnetocrystalline anisotropy constant was enhanced from 0.57 MJ/m3 in pure Fe16N2 to 1.58 MJ/m3 and 0.89 MJ/m3 in Fe16N2/Ag/Fe16N2 and Fe16N2/Au/Fe16N2 multilayer systems, respectively. This enhancement in magnetocrystalline anisotropy results in an enhancement of the coercive field. The coercive fields were about 30 and 16.7 kOe in the Ag and the Au multilayer systems, respectively. Overall, we found substantial enhancements in the magnetocrystalline anisotropy constant and the coercive field due to the interface effect. This finding may suggest that the Fe16N2/Ag/Fe16N2 and the Fe16N2/Au/Fe16N2 structures can be utilized for potential rare-earth-free permanent magnets.

We investigated the electronic structure and magnetic properties of hydrogenated bilayer graphene and graphene/h-BN heterostructure as a function of applied uniaxial compression normal to the interface plane using van der Waals density functional theory. The H atoms preferred a cluster formation was found in the hydrogenated bilayer graphene and graphene/h-BN systems with a non-magnetic ground state. With increasing external pressure, the equivalence of two sublattices in graphene was broken because of the interaction between graphene and the underlying layer and the site dependent adsorption energy difference was greatly enhanced with the applied pressure. This resulted in a transition from an NM ground state to a ferromagnetic in hydrogenated bilayer graphene and graphene/h-BN heterostructure. Thus, we propose that the magnetic property can be manipulated by external pressure and that hydrogenated systems can be utilized for potential spintronics applications at low H concentrations.

Using the first principles method, we studied the electronic structure and magnetocrystalline anisotropy of site dependent 4d, 5d element doping in α″-Fe16N2. We found that different Fe sites contributed differently for magnetocrystalline anisotropy. For instance, on d-site doping, we obtained perpendicular magnetocrystalline anisotropy while the h-site doping resulted in an in-plane magnetocrystalline anisotropy in all the studied systems. The impurity doping induces local lattice distortions near the impurity site. However, the volume of the cell and total magnetic moment of the doped systems were not much affected. This local lattice distortion together with the spin-orbit coupling effect associated with heavy 4d, 5d element mainly contributed to enhancing the magnetocrystalline anisotropy. The enhancement of the magnetocrystalline anisotropy results in almost 15 to 67% enhancement of the coercivity for 4d element doping while we found 80 to 137% enhancement for 5d element doping. The maximum energy products were also enhanced compared to the pure α″-Fe16N2. The maximum enhancement was observed in Rh and Pt doped systems where the energy products were 119–120 MGOe. These results may suggest that substitutional doped α″-Fe16N2 system can be used as potential rare earth free permanent magnet.

We investigated the electronic structure, adsorption energies, magnetic properties, dipole moment and work function of metal adatoms (Mg, Cr, Mo, Pd, Pt, and Au) adsorption on a blue phosphorene monolayer. For Mg, Pt and Au metals, the most stable state was found in hollow site while for Cr, Mo and Pd metals we found an adsorption in valley site. We suggest that the Pd and Pt atoms prefer 2D growth mode while the Mg, Cr, Mo and Au atoms prefer 3D island growth mode on monolayer phosphorene. The electronic band structures and magnetic properties were dependent on the doping site and dopant materials. For instance, the semiconducting features were preserved in Mg, Pd, Pt, and Au doped systems. However, the Cr and Mo doped systems displayed half-metallic band structures. The total magnetic moment of 4.05, 2.0 and 0.77 μ B / impurity atom were obtained in Cr, Mo and Au doped systems whereas the Mg, Pd and Pt doped systems remained nonmagnetic. We also investigated the magnetic interaction between two transition metal impurities. We observed ferromagnetic coupling between two transition metal impurities in Cr and Mo doped systems while the Au doped system displayed almost degenerated magnetic state. For Mg, Cr, and Mo adsorptions, we found relatively large values of dipole moments compared to those in the Pd, Pt and Au adsorptions. This resulted in a significant suppression of the work function in Mg, Cr and Mo adsorptions. Overall, adsorption can tune the physical and magnetic properties of phosphorene monolayer.

Using the density functional theory incorporated with a non-equilibrium Green's function (NEGF) technique, we explored the bias-dependent transport of tilted phosphorene nanoribbons. Herein, we considered three types of nanoribbons: self-passivated (TPNRself), H-passivated (TPNRH), and O-passivated (TPNRO) systems. The TPNRself showed an indirect band gap of 0.53 eV, whereas the TPNRH displayed a direct band gap of 1.32 eV. In TPNRO, we observed a spin-polarized band structure with a spin-dependent band gap. We found that the bias-dependent I-V curve was dependent on the passivation effect. In TPNRself and TPNRH, the current monotonically increased with an external bias, but the magnitude of the current in TPNRself was more than 10 times than that in TPNRself. Unlike the I-V characteristics in TPNRself and TPNRH, the current in TPNRO almost vanished beyond an external bias of 1.7 V. Mostly, the bias-dependent I-V was interpreted based on the band structure in the lead parts. However, we found that this conventional approach was not sufficient to analyze the I-V curve. Indeed, we showed that the detailed I-V curve could be understood by calculating the bias-dependent density of states in the scattering part related to the transmission channel. It was also found that the electron flow channel was dependent on the passivation effect and uniformly distributed over the entire nanoribbon in TPNRself and TPNRH. In contrast, the electron flowed mostly along the edge line in TPNRO. Moreover, we have found that spin polarization in the conduction current can be manipulated by an external bias, and this may suggest that the TPNRO can be utilized for potential spintronic applications.

Magnetic proximity effect can be used to tailor the magnetic ground state and valley polarization in the monolayer of transition metal dichalcogenides. Thus, we explore the effect of biaxial tensile and compressive strain on valley polarization in the WSe2/CrSnSe3 heterostructures with different stacking orders systematically. The indirect band gaps in the two most stable stackings; hollow (0.27 eV) and top (0.33 eV) were further enhanced to 0.35 eV under tensile strain while suppressed to almost 0.13 eV under compressive strain. The heterostructures had a FM ground state with a total magnetic moment per unit cell of 6 µB in pristine as well as strained structures. In hollow stacking and compressively strained structures, we obtained a perpendicular magnetocrystalline anisotropy, while the top stacking and tensile strain structures had small in-plane anisotropy. An enhancement was found in Curie temperature from 73 K in pristine to 128 K in a 6 % tensile strained structure. The valley splittings found in pristine hollow (4 meV) and top (9 meV) stacked heterostructures were further enhanced to 29 meV and 22 meV at 5 % compressive strain respectively. This enhancement was attributed to the increased spatial dependence of the charge density along K+ and K- directions of the Brillouin zone, which give rise to the different local dipolar fields at these valleys. Our results suggest that strain could be an effective way to control or tune the valley splitting in WSe2/CrSnSe3 heterostructures.

The electronic structure and the magnetocrystalline anisotropy of impurity (Li, Be, B, C, and N) doped α″-Fe16N2 were studied by using full potential linearized augmented plane wave method (FLAPW). From the formation energy calculations, it was evident that the 2s and 2p elements except Li could be easily doped into pure α″-Fe16N2. The impurity doping induced local lattice distortions near the impurity site and the magnetic moment near the impurity atom was substantially suppressed. However, the volume of the cell and the total magnetic moment of the doped systems were weakly suppressed compared to the pure α″-Fe16N2. Despite this relatively weak suppression in magnetization, the local distortion contributed to enhancing the magnetocrystalline anisotropy. Due to this enhancement in the anisotropy, the coercive field was also enhanced about 12–16% compared with that in pure structure. Along with the enlarged coercive field, the energy product was also increased. These results may suggest that impurity doped α″-Fe16N2 can be used as potential rare earth free permanent magnet.

We explored a two-dimensional (2D) binary compound consisting of arsenic and phosphorus by means of density functional theory (DFT) calculations. The geometry, electronic structure, and optical properties of monolayer, few-layer and bulk As 1-x P x compounds with different composition ratio were investigated. We can achieve a more continuous tuning in band gap by change the composition and thickness. The band gap of As 1-x P x monolayer was almost the same as that of phosphorene monolayer, regardless of the As concentration. However, the band gaps of few-layer systems decrease significantly. In the case of few-layer systems, they can possess various band gap values those the pristine phosphorus system cannot reach. The direct-indirect band gap transition occurred at a certain threshold when the As concentration continuously increased. The more concentration of As was, the faster band gap decreased. The band gaps of their bulk systems were in the range of 0.3–0.4 eV, which is very close to that of bulk phosphorus and this was not sensitive to the composition and topological arrangement. The dielectric function calculations revealed that the optical properties of the arsenic phosphide systems were highly tunable by changing the composition and thickness. Overall, we propose that the tunable electronic and optical properties of the As 1-x P x binary compounds make them great candidates for application in the field of electronics and optoelectronics.