Interlayer coupling and diode characteristics of heterostructures of solution processed MoS2:ReS2 nanocrystals

Heterostructures of MoS2 and ReS2 nanocrystals were prepared in the solution phase by synthesizing the nanocomposite of these two transition metal dichalocogenides (TMDs). The heterostructure of the bulk nanocrystals of these two TMDs is shown to be forming type II heterojunction, favouring n-n junction like characteristics, exhibiting donor-acceptor like behavior. Raman spectroscopy, XPS, UV-Vis absorption measurements and EDX analysis revealed interlayer coupling, charge transfer interaction between the two TMDs and creation of sulfur vacancies in the nanocomposites. Presence of sulfur vacancies is suggested to further reduce the electron injection barrier at the ITO/MoS2 interface, favouring flow of larger current in the forward bias direction. This conclusion was supported by the electrical characteristics of the drop cast films of the nanocomposite revealing diode characteristics with the rectification ratio of about 25. The ideality factor estimated was slightly higher which could be due to defect and trap states at the interface between the two TMDs. The study shows that by simple solution phase route of the bulk like nanocrystals, diode behavior can be obtained that can be useful for bulk heterojunction solar cell applications.