The versatile characteristics of Ars/SGaInS van der Waals heterostructures.

Two-dimensional (2D) materials with upright stacking form layered van der Waals heterostructures (vdWHs) are currently believed to be attractive prospects for optoelectronic, photocatalytic, and thermoelectric devices because they can merge the capabilities of distinct 2D materials. Herein, we evaluate the electronic, optical, photocatalytic, and thermoelectric response of model-I and model-II of Ars/SGaInS vdWHs via first-principles computations. The energetic, dynamical, and thermal stabilities of these vdWHs suggest great promise in experimental functionality. Model-I and model-II are indirect semiconductors with type-II band alignment and bandgaps of 1.53 eV and 1.86 eV, respectively. The built-in electric field considerably accelerates the transmission of electrons from the Ars layer to the SGaInS layer. Compared to pristine monolayers, both models contain appropriate band edge positions to ensure overall water splitting efficiently. Interestingly, at -8% compressive strain, model-I secures type-III band alignment, which is very advantageous for field-effect transistors. In the visible and ultraviolet zones of the radiating spectrum, the proposed vdWHs significantly improved the absorption spectra, and the biaxial strain also has a considerable impact on optical absorption. The investigated vdWHs have high Seebeck coefficients and substantial electrical conductivities, which contribute to high power factor values, particularly at 700 K. The outcomes specify that our designed Ars/SGaInS vdWHs have a multifunctional character that can perform a better role in optoelectronics, photovoltaics, photocatalysis, tunneling field effect transistors, and thermoelectric devices.

High thermoelectric performance of two-dimensional SiPGaS/As heterostructures.

Thermoelectric technology holds great promise as a green and sustainable energy solution, generating electric power directly from waste heat. Herein, we investigate the thermoelectric properties of SiPGaS/As van der Waals heterostructures by using computations based on density functional theory and semiclassical Boltzmann transport theory. Our results show that both models of SiPGaS/As van der Waals heterostructures have low lattice thermal conductivity at room temperature (300 K). Applying 4% tensile strain to the models leads to a significant enhancement in the figure of merit (ZT), with model-I and model-II exhibiting ZT improvements of up to 24.5% and 14.8%, respectively. Notably, model-II outperforms all previously reported heterostructures in terms of ZT value. Additionally, we find that the maximum thermoelectric conversion efficiency (η) for model-II at 4% tensile strain reaches 23.98% at 700 K. Our predicted ZTavg > 1 suggests that these materials have practical potential for thermoelectric applications over a wide temperature range. Overall, our findings offer valuable insights for designing better thermoelectric materials.

Enhanced visible-light-driven photocatalytic activity in SiPGaS/arsenene-based van der Waals heterostructures.

Van der Waals heterostructures (vdWHs) showcase robust and tunable light-matter interactions, establishing an intriguing realm for investigating atomic-scale photocatalytic properties. Here, we employ ab initio methods to study the photocatalytic and optical properties of semiconducting SiPGaS/arsenene-based vdWHs with a type-II band alignment. Across the heterointerfaces, there exists significant built-in electric fields and large potential drop, in turn facilitating the spatial separation of photo-generated electron-hole pairs. These vdWHs further possess high carrier mobility in the order of 102 cm2V⁻1S⁻1, which combining with appropriate band edge positions, endow the vdWHs an absorption coefficient of ∼105 cm⁻1 to harvest a maximal portion of the solar spectrum for visible-light-driven photocatalytic applications. Our findings also reveal transition of the type-II band alignment in a type-III configuration via compressive strain for tunneling field-effect transistor application. Furthermore, both types of vdWHs exhibit enhanced suitability for photocatalysis under conditions with a pH of 2.

Electronic, mechanical, optical and photocatalytic properties of two-dimensional Janus XGaInY (X, Y ;= S, Se and Te) monolayers.

Janus monolayers with breaking out-of-plane structural symmetries and spontaneous electric polarizations offer new possibilities in the field of two-dimensional materials. Due to the depletion of fossil fuels and serious environmental problems, there has been a growing interest in the conversion of water and solar energy into H2 fuels in recent years. In this research, Janus XGaInY (X, Y = S, Se and Te) monolayers are predicted as promising solar-water-splitting photocatalysts. Based on first-principles calculations, the electronic, mechanical, optical and photocatalytic properties of Janus XGaInY (X, Y = S, Se and Te) monolayers are investigated. These Janus monolayers are structurally stable semiconductors with indirect bandgaps, except for SGaInSe, SGaInTe, TeGaInS and SeGaInTe. Their energy bandgaps extend from 0.74 to 2.66 eV at a hybrid density functional level, which is crucial for broadband photoresponses. Moreover, these Janus monolayers not only show strong light absorption coefficients greater than 104 cm-1 in the visible and ultraviolet regions but possess suitable band edge positions for water splitting. Our findings reveal that these Janus monolayers have a potential for application in the fields of optoelectronic and photocatalysis.