2D layered CrS2 flakes down to the monolayer are successfully synthesized, and different phases of CrS2 are observed and exhibit direct band gap p-type semiconducting, metallic, and semi-metallic behaviors, respectively.

2D transition metal dichalcogenides (TMDs) are a promising material system for optoelectronic applications. However, their key figure of merit, the room‐temperature photoluminescence (PL), is extremely low. To overcome this challenge, TMDs need interfacing with other semiconducting materials and discover the underlying physical phenomena. Herein, the optical properties and PL mechanisms of molybdenum disulfide‐organic perylene derivative (PDI/MoS2) based type‐II heterostructures, i.e., PTCDA/MoS2 and PTCDI‐Ph/MoS2, are studied experimentally and theoretically. The PL of MoS2 in PTCDA/MoS2 is enhanced, while a dramatic PL quenching of MoS2 is observed on PTCDI‐Ph/MoS2. The significant radiative PL enhancement of PTCDA/MoS2 is primarily due to the bandgap reduction, high exciton/trion ratio, and epitaxial growth of PTCDA. In contrast, “trap‐like” states in heterointerface, relatively low exciton/trion ratio, and less ordered morphology are responsible for PL quenching of PTCDI‐Ph/MoS2 heterostructure. These findings would provoke a new way to engineer the light‐matter interactions in organic/TMD hybrids, which enables light‐emitting, light‐harvesting applications, and neuromorphic devices.

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Heterostructures built from 2D materials and organic semiconductors offer a unique platform for addressing many fundamental physics and construction of functional devices. Interfaces play a crucial role in tailoring the heterostructure properties. Here, density functional theory computations are performed to explore the interfacial properties of heterostructures made of group VI transition metal dichalcogenides (TMD) and organic molecules such as perylene tetracarboxylic dianhydride (PTCDA) and pentacene. First principle calculations predict that the organic pentacene layer exhibits covalent interfacing with MoSe2 and WSe2, while the interface of other studied TMD/organic heterostructures form van der Waals (vdW) interfaces. Owing to the different molecular geometry of PTCDA and pentacene in their respective heterostructures, the work function can be modulated of the order of 1.0 eV in comparison with pure monolayer MX2 in MX2/pentacene (M = Mo, W; X = S, Se) heterostructures, while the change of work function in MX2/PTCDA (M = Mo, W; X = S, Se) is negligible (order of 0.1 eV) in comparison with pure monolayer MX2. This study will be helpful to design high‐performance optoelectronic devices based on TMDs and organic semiconductors.

Heterostructures built from two-dimensional (2D) materials and organic semiconductors offer a unique platform for addressing many fundamental physics and construction of functional devices by taking both the advantages of 2D...