Modulated Photoluminescence of Single‐Layer MoS₂ via Nanostructured SrTiO₃ Surface

Abstract

innovative devices such as synapse transistor, [15][16][17] nonvolatile memory, [18,19] nanopower generators, [20] and so on. For most application circumstances, a proper support is usually necessary which either holds the transferred MoS 2 thin film or directly serves as the synthetic substrate. In fact, recent studies have witnessed the effective modulation of the properties of the MoS 2 films rendered from the different supports. [21][22][23][24][25][26][27][28][29][30][31][32] On the one hand, distinct substrate materials can induce different charge separation at the interfaces and establish varied dipole fields at the corresponding heterojunctions, which strictly depends on the actual components as well as the atomic structures of the interfaces. [33,34] On the other hand, additional tuning effects can be obtained via nanostructuring the substrate surface, which has provided a more-open strategy for tuning the transportation and luminescence properties of MoS 2 . [35][36][37][38][39][40][41][42][43][44] However, in the latter case, the substrate surfaces were usually prepared through complicated and expensive processes such as nanosphere or electron beam lithographies. Meanwhile, onsite synthesis of the MoS 2 films has not been realized on these sophisticatedly structured substrates. The transfer process of the MoS 2 films inevitably arouses the formation of unwanted film wrinkles and interfacial contaminants, which hinders the optimization of the obtained heterostructures. [24,45] Nevertheless, direct synthesis of high quality 2DMs on the largely corrugated substrate remains an urgent yet challenging task. The structure and morphology of the substrate surface play critical roles in tuning the properties of the supported two-dimension materials (2DM). In this work, a simple strategy to engineer the SrTiO 3 single crystal into a trenched structure which is composed of atomically flat terraces and high steps of several nanometers is developed. Through the conventional chemical vapor deposition method, high quality single-layered MoS 2 nanosheets are successfully fabricated directly on the trenched SrTiO 3 (Tr-STO) substrate, which thus result in a heterostructure with well-defined interface and controllable corrugated morphology. The corrugated MoS 2 /Tr-STO sample displays a drastically suppressed photoluminescence as compared to those grown on atomically flat substrates. Detailed scanning probe microscopy in combination with optical spectroscopy measurements demonstrates that the photoluminescence quenching occurs exclusively in the MoS 2 area carpeting the high SrTiO 3 steps, which can be attributed to the significantly reduced bandgaps hence massively enriched free charges in these regions. This work not only provides a new strategy to tailor the 2DM properties by simply engineering the substrate surface corrugations, but also brings deep insights into the dependence of properties of the hybridized system on the interface morphologies.

Development of Sustainable Catalyst Coating of Ni2P Engineered SrTiO3 Nanocubes for Hydrogen Generation

“…The photochemical applications of pristine SrTiO 3 are not very surprising due to its wide band gap . However, tunable morphologies and photochemical properties for optimizing the band gap makes it suitable for water splitting applications . Numerous works have been already reported for altering the photocatalytic properties of SrTiO 3 : for example, morphological tailoring for influencing the active surface area, heteroatom/group doping for tuning the effective band gaps, introducing defects for influencing the absorption spectrum in the visible region, and cocatalyst loading for reducing the electron–hole recombination rates. , Even though the formation of the heterojunction with metal phosphides is one such effective technology, it is not widely explored in altering the band gap of SrTiO 3 .…”