Charge Transfer and Interface Engineering of the Pentacene and MoS₂ Monolayer Complex

Abstract

Molecular doping of monolayer MoS2 provides a great opportunity to modulate its electronic properties for the potential applications in high performance devices. Density functional theory computations are performed to investigate the charge transfer and electrostatic potential modulation upon the adsorption of pentacene molecule on the surface of MoS2 monolayer (ML). Theoretical calculations indicate that interfacial charge transfer is negligible between pentacene and 2H‐MoS2 ML while significant in the pentacene/1T‐MoS2 ML complex, which is attributed to the match of energy levels near the Fermi level in the latter case. Moreover, molecular doping of pentacene induces substantial structure changes of the substrate resulting in large adsorption energy, which helps stabilize the 1T‐MoS2 ML. Depending on different substrate phases and doping configurations, the interfacial dipole barrier and related work function of MoS2 ML may be modulated in a wide range of the order of about 1 eV. The findings therefore shed light on the possibility of developing the desired organic/inorganic complex for electrical and optoelectronic devices by molecular doping via charge transfer modulation and interface engineering.

MoS2 and Perylene Derivative Based Type‐II Heterostructure: Bandgap Engineering and Giant Photoluminescence Enhancement

“…Besides, the epitaxial layer of PTCDA molecules may passivize the intrinsic defect due to S vacancy in the MoS 2 monolayer, which is related to nonradiative PL. [60] To estimate the exact amount of charge transfer between the PDI molecule and the MoS 2 monolayer, we performed the differential charge density Δρ(r) in two different heterostructures. To support this argument we estimate the sharpness of the band edges (Figure 4e) from Urbach tails which are derived from the steady-state PL spectrum I(v) via the van Roosbroeck-Shockley equation, [39,56] band-edge sharpness of PTCDA modified MoS 2 heterostructure.…”

“…This suggests a relatively weak interaction between the nonplanar PTCDI-Ph molecules and the MoS 2 -ML substrate and relatively strong for the planar PTCDA molecule with the MoS 2 -ML substrate, which indicates that the strong adsorbate-substrate interactions may also help stabilize the MoS 2 monolayer. [60] To estimate the exact amount of charge transfer between the PDI molecule and the MoS 2 monolayer, we performed the differential charge density Δρ(r) in two different heterostructures. The isosurface plots of Δρ(r) for PTCDA/MoS 2 and PTCDI-Ph/MoS 2 are shown in Figure 5e (inset: top/bottom).…”

Theoretical Study of Interfacial and Electronic Properties of Transition Metal Dichalcogenides and Organic Molecules Based van der Waals Heterostructures

“…Furthermore, DFT calculations suggest that interfacial charge transfer is negligible between pentacene and semiconducting monolayer (2H‐MoS 2 ), while significant in the combination of metallic MoS 2 (1T‐MoS 2 ) and pentacene which was attributed to the match of energy levels near the Fermi level of the metallic 1T‐MoS 2 with the pentacene. [ 29 ]…”

2D–Organic Hybrid Heterostructures for Optoelectronic Applications

“…Lattice matching at the interface is not a critical constraint for vdW 2D–organic hybrid heterostructures, unlike the case of epitaxially grown conventional heterostructures . While this heterostructure scheme provides a higher degree of freedom for material selection, the physical properties of the heterostructure become complicated because of the introduction of sources of trap states, such as point and line defects, at the interface; this, in turn, can cause nonradiative carrier recombination and Fermi‐level pinning .…”

“…In 2D–organic composites, the charge transport of the blends is strongly associated with the relative arrangement of the 2D nanosheets in the matrix. Furthermore, the stacking distance of the 2D material and the organic material will also affect the conductivity and charge transfer between them …”