Site-controlled interlayer coupling in WSe2/2D perovskite heterostructure

Abstract

Interlayer excitons (IXs) formed in transition metal dichalcogenides (TMDs)/two-dimensional (2D) perovskite heterostructures are emerging as new platforms in the research of excitons. Compared with IXs in TMD van der Waals heterostructures, IXs can be robustly formed in TMDs/ 2D perovskite heterostructures regardless of the twist angle and thermal annealing process. Efficient control of interlayer coupling is essential for realizing their functionalities and enhancing their performances. Nevertheless, the study on the control of interlayer coupling strength between TMD and 2D perovskites is elusive. Therefore, we realize the control of interlayer coupling between monolayer WSe 2 and (iso-BA) 2 PbI 4 with SiO 2 pillars in situ. An abnormal 10-nm blue shift and 2.5 times photoluminescence intensity enhancement were observed for heterostructures on the pillar, which was contrary to the red shift observed in TMD heterobilayers. We attributed the abnormal blue shift to the enhanced interlayer coupling arising from the reduced gap between constituent layers. In addition, IXs became more dominant over intralayer excitons with enhanced coupling. The interlayer coupling could be further engineered by tuning the height (h) and diameter (d) of pillars. In particular, an additional triplet IX showed up for the pillar with an h/d ratio of 0.6 due to the symmetry breaking of monolayer WSe 2 . The symmetry breaking also induced an anisotropic response of IXs. Our study is beneficial for tuning and enhancing the performance of IX-based devices, exciton localization and quantum emitters.

Navigating the Site-Distinct Energy Conversion Properties of Perovskite Quantum Wells

“…Forming a type-II band hierarchy, the energy gap between the VBM of the 2D HP side and the CBM of the MoS 2 side is <0.8 eV, hence granting access to a photoresponse to the telecommunication region (∼1550 nm) . Li’s group introduced the property-manipulable interlayer excitons of a WSe 2 /(iso-BA) 2 PbI 4 heterojunction . The heterostructure is grown on a Si pillar, of which the size and shape would pose a strain effect on the WSe 2 layer to break its symmetry.…”

“…172 Li's group introduced the property-manipulable interlayer excitons of a WSe 2 /(iso-BA) 2 PbI 4 heterojunction. 173 The heterostructure is grown on a Si pillar, of which the size and shape would pose a strain effect on the WSe 2 layer to break its symmetry. Such strain-induced symmetry breaking results in anisotropic interlayer excitonic emissions with linear dichroism up to 1.7.…”

Two/Quasi-two-dimensional perovskite-based heterostructures: construction, properties and applications

“…While for 2D perovskites/monolayer TMDs heterostructures, the interlayer coupling can be robustly formed without considering the rotation angle and thermal annealing, which makes the fabrication process much easier. In addition, the interlayer exciton emission intensity in 2D perovskite/monolayer TMDs heterostructures can be readily controlled via external strain, providing another degree of freedom to tune the interlayer coupling strength [171]. Importantly, those interlayer excitons also exhibit circularly polarized light emission in chiral 2D perovskite/WSe 2 heterostructures under linearly polarized light excitation, suggesting that the valley polarization persists for interlayer excitons.…”

High‐Resolution Patterning of 2D Perovskite Films through Femtosecond Laser Direct Writing

“…[14,15] In addition, with the reserved remarkable optoelectronic properties, the 2D perovskites tend to be promising candidates for stable and efficient optoelectronic devices. [16,17] For many practical applications, such as pixel arrays for displays, [18,19] image sensor arrays, and fluorescent anti-counterfeiting labels, [20][21][22][23][24] it is critical to develop an efficient technique to achieve controllable and precise fabrication of patterned 2D perovskite films. [25,26] To date, several methods have been proposed to fabricate patterned perovskites, such as photolithography, [26,27] micro/nanoimprinting, and inkjet printing.…”