Robust Interlayer Coupling in Two-Dimensional Perovskite/Monolayer Transition Metal Dichalcogenide Heterostructures

Abstract

Interlayer excitons have been extensively studied in monolayer transition metal dichalcogenide (TMD) heterobilayers mainly due to the long lifetime, which is beneficial for a wide range of optoelectronic applications. To date, the majority of investigations of interlayer excitons in TMD heterobilayers have been focusing on the geometric arrangement of structures, spin–valley lifetime, and interlayer valley excitons with interlayer hopping rules. Nevertheless, interlayer excitons in TMD heterobilayers strongly depend on the local atomic registry and coupling strength, which increase the complexity of the device fabrication. Here, we report pronounced interlayer exciton emission in two-dimensional (2D) perovskite/monolayer TMD heterostructures without the need of thermal annealing or specific geometric arrangements, and the interlayer exciton emission is rather general among 2D perovskites and monolayer TMDs. Such interlayer exciton emission completely dominates the emission spectrum at 78 K regardless of the stacking sequence, suggesting the robust interlayer coupling in 2D perovskite/monolayer TMD heterostructures. Furthermore, the interlayer exciton emission shows a large blue-shift with increasing laser intensity due to the repulsive dipole–dipole interaction and can persist above 220 K. Importantly, the interlayer exciton emission also possesses robust circular polarization in chiral 2D perovskite/monolayer WSe2 heterostructures, which can be applied to manipulate the valley degree of freedom for valleytronic devices. Our findings would provide a favorable platform to explore interlayer coupling and related physical processes in 2D perovskites and TMDs and further provoke more investigations into the understanding and controlling of excitonic effects and associated optoelectronic applications in van der Waals heterostructures over a broad-range spectral response.

Recent Progress on Two-Dimensional Materials

“…So far, many types of 2D materials have been fabricated into chiral ones, including the 2D perovskites 302,[663][664][665][666][667][668][669][670] , graphene [671][672][673] , TMDs [674][675][676][677] , 2D organic nanoassemblies 678 and many more. A key scientific issue is how the chirality is originated and how to endow the 2D materials with chirality.…”

Capturing Mobile Lithium Ions in a Molecular Hole Transporter Enhances the Thermal Stability of Perovskite Solar Cells

“…For instance, the integration of 2D transition metal dichalcogenides in PSCs has shown significant improvement in both environmental and thermal stabilities of the devices. [11][12][13][14] Dopant-free MHT has been also suggested to be one of solutions to solve the thermal instability. However, PCE is sacrificed due to the lowered conductivity in the absence of dopants and furthermore PCE of about 20% is still inferior to that of the conventional devices using additive (>23%).…”

Nonvolatile electrical switching of optical and valleytronic properties of interlayer excitons

“…Through electrical field or doping, we can modulate the emission intensity and wavelength of the IXs 5 , and even switch its polarization 6 . Recently, IXs in the HSs stacked by other layered materials such as 2D perovskites and InSe with TMDs monolayer have been demonstrated and can be utilized in mid-infrared photodetections 7 , 8 .…”