Cataloguing MoSi₂N₄ and WSi₂N₄ van der Waals Heterostructures: An Exceptional Material Platform for Excitonic Solar Cell Applications

Abstract

2D materials van der Waals heterostructures (vdWHs) provide a revolutionary route toward high‐performance solar energy conversion devices beyond the conventional silicon‐based pn junction solar cells. Despite tremendous research progress accomplished in recent years, the searches of vdWHs with exceptional excitonic solar cell conversion efficiency and optical properties remain an open theoretical and experimental quest. Here, this study shows that the vdWH family composed of MoSi2N4 and WSi2N4 monolayers provides a compelling material platform for developing high‐performance ultrathin excitonic solar cells and photonics devices. Using first‐principle calculations, 51 types of MoSi2N4 and WSi2N4‐based [(Mo,W)Si2N4] vdWHs composed of various metallic, semimetallic, semiconducting, insulating, and topological 2D materials are constructed and classified. Intriguingly, MoSi2N4/(InSe, WSe2) are identified as Type II vdWHs with exceptional excitonic solar cell power conversion efficiency reaching well over 20%, which are competitive to state‐of‐the‐art silicon solar cells. The (Mo,W)Si2N4 vdWH family exhibits strong optical absorption in both the visible and UV regimes. Exceedingly large peak UV absorptions over 40%, approaching the maximum absorption limit of a freestanding 2D material, can be achieved in (Mo,W)Si2N4/α2‐(Mo,W)Ge2P4 vdWHs. The findings unravel the enormous potential of (Mo,W)Si2N4 vdWHs in designing ultimately compact excitonic solar cell device technology.

Understanding Electronic Properties and Tunable Schottky Barriers in a Graphene/Boron Selenide van der Waals Heterostructure

“…The tunneling probability across the vdW interface can be calculated as follows: TP = exp ( − 2 w T B ℏ 2 m e h T B ) Here, h TB and w TB are the barrier height and width of the tunneling potential barrier, respectively. m e and ℏ are the mass of the free electron and reduced Planck’s constant, respectively.…”

“…The tunneling probability across the vdW interface can be calculated as follows: 27 = i k j j j y potential of the graphene/BSe heterostructure as depicted in Figure 3(d). The calculated h TB and w TB are 3.26 eV and 1.75 Å, respectively.…”

“…23−26 Recently, making a heterostructure between two or more different 2D materials has been considered to be an effective tool for enhancing the properties and expanding the application possibilities of 2D materials. 27 Heterostructures are commonly made using different strategies, including molecular beam epitaxy (MBE) 28 and chemical vapor deposition (CVD). 29 Nowadays, there are a large number of heterostructures that have been synthesized and predicted, and new ones are being developed all the time.…”

Two-Dimensional Ferroelectric C2N/In2Se3 Heterobilayer with Tunable Electronic Property and Photovoltaic Effect

“…Although the C 2 N/up-In 2 Se 3 heterostructure belongs to the type-I heterostructure, the E -field from −0.1 to 0.4 V/Å and the compressive strain can make it transform into the type-II one, as shown in Figures S5, S6, and b,d. Figure S7 displays the projected band structures of the C 2 N/up-In 2 Se 3 heterostructure under the E -field of 0.1 V/Å and the strain of −2% using the HSE06 scheme, in which the corresponding PCEs are high up to 24.03 and 24.00%, respectively, higher than those of MoSi 2 N 4 /InSe and MoSi 2 N 4 /WSe 2 heterostructures . The above results reveal the potential applications of the C 2 N/In 2 Se 3 heterostructures in the solar cell field.…”

Electronic structure and optical spectra of MSi2N4 (M = Mo, Ta, V) materials with single-atom decoration: a first-principles study

“…22–24 For instance, the type-II WSe 2 /MoSi 2 N 4 heterojunction 25 can boost carrier separation and prolong carrier lifetime, which is beneficial for photocatalytic water splitting. The WSi 2 N 4 /MoSi 2 N 4 van der Waals (vdW) heterostructure 26 shows superior light absorption in the visible and ultraviolet (UV) regions, making it highly promising for solar cell device. The transition metal decorated MoSi 2 N 4 monolayer is systematically investigated by Lu et al 27 and Xun et al , 28 which demonstrated novel catalytic design strategy for oxygen evolution and CO 2 conversion, respectively.…”