Study of Two-Dimensional Janus WXY (X≠Y= S, Se, and Te) Trilayer Homostructures for Photovoltaic Applications Using DFT Screening of Different Stacking Patterns

Abstract

Based on the first-principles density functional theory, Janus WXY (X ≠ Y = S, Se, and Te) trilayer homostructures for different stacking patterns are studied in this work to analyze their appropriateness in fabricating photovoltaic (PV) devices. A total of fifteen trilayer homostructures are proposed, corresponding to the suitable five stacking patterns, such as AAA, AA′A, ABA, AB′A, and A′BA′ for each Janus WXY (X ≠ Y = S, Se, and Te) material. Structural and energetic parameters for all the fifteen structures are evaluated and compared to find energetically stable structures, and dynamic stability is confirmed by phonon dispersion curves. All these configurations being homostructure, lattice mismatch is found to be very low (∼0.05%), unlike heterostructure, making them feasible for optoelectronics and PV applications. WSSe AAA, WSSe AA′A, and WSeTe AA′A are dynamically stable along with negative binding energy and show type-II band alignment, enabling effective spatial carrier separation of photogenerated carriers. The optical properties of dynamically stable WSSe AAA and WSSe AA′A structures are also calculated, and the absorption coefficients at the visible light region are found to be ∼3.5 × 10 5 cm –1 , which is comparable to the perovskite material absorption coefficient. Moreover, we have compared the optical characteristics of dynamically stable WSSe AAA and WSSe AA′A structures with their monolayer structures to realize the significance of stacking trilayer structures. Electrical properties such as mobility and conductivity for dynamically stable WSSe AAA and WSSe AA′A structures are evaluated to suggest them as a probable efficient material in PV technology.

To the Stability of Janus Phases in Layered Trichalcogenide MPX3 Crystals: Insights from Experiments and Theory

“…One of the intrinsic properties of Janus structures is high out-of-plane dipole moment, which might lead to their instability . This can be compensated by employing a polar substrate during the synthesis as it was realized in the case of MoSSe grown on the SiO 2 /Si and polished sapphire substrates. , These experimental studies stimulated enormous computational activity, and many theoretical studies have been published in the last few years speculating about prospects of the freestanding 2D Janus monolayers for applications in orbitronics, optoelectronics, photovoltaic technology, and photocatalysis. , At this, the stability of these hypothetical materials and the possibility of their experimental implementation are rarely discussed …”

Metal to semiconductor switching in the AgTe monolayer via decoration with alkali metal and alkaline earth metal atoms: a first-principles perspective

“…The electron and hole mobilities are evaluated from the Boltzmann transport equation (BTE) as follows: 47,48 where, k , n , q , ε kn , v kn , and τ kn stand for electron momentum, band index, charge, energy, electron velocity, and relaxation time, correspondingly. The electronic distribution of the carrier is also equated from the BTE as: 47,48 And the inverse relaxation time is equated by: 47,48 where, represents the transition rate from state kn to k ′ n ′.…”

“…The electron and hole mobilities are evaluated from the Boltzmann transport equation (BTE) as follows: 47,48 m ¼ À2q…”

“…where, k, n, q, e kn , v kn , and t kn stand for electron momentum, band index, charge, energy, electron velocity, and relaxation time, correspondingly. The electronic distribution of the carrier is also equated from the BTE as: 47,48…”

Pressure-Driven Structural and Electronic Transitions in a Two-Dimensional Janus WSSe Crystal

“…The electrical conductivity of WSSe is 4.94 × 10 −6 S cm −1 at the lowest measured pressure of 1.9 GPa, which is close to the previously available result with the electrical conductivity of 3.94 × 10 −6 S cm −1 under ambient conditions and validates the reliability of our electrical conductivity measurements. 52 Between 1.9 and 14.9 GPa, the electrical conductivity of the sample markedly raised by more than 3 orders of magnitude at a large rate of 0.26 S cm −1 GPa −1 , followed by the gentle enhancement in electrical conductivity at a moderate speed of 0.16 S cm −1 GPa −1 at 14.9−23.2 GPa. After 25.8 GPa, weak pressure-dependent electrical conductivity at a minor slope of 0.055 S cm −1 GPa −1 was detectable.…”