Electronically Coupled 2D Polymer/MoS₂ Heterostructures

Abstract

Emergent quantum phenomena in electronically coupled two-dimensional heterostructures are central to next-generation optical, electronic, and quantum information applications. Tailoring electronic band gaps in coupled heterostructures would permit control of such phenomena and is the subject of significant research interest. Two-dimensional polymers (2DPs) offer a compelling route to tailored band structures through the selection of molecular constituents. However, despite the promise of synthetic flexibility and electronic design, fabrication of 2DPs that form electronically coupled 2D heterostructures remains an outstanding challenge. Here, we report the rational design and optimized synthesis of electronically coupled semiconducting 2DP/2D transition metal dichalcogenide van der Waals heterostructures, demonstrate direct exfoliation of the highly crystalline and oriented 2DP films down to a few nanometers, and present the first thickness-dependent study of 2DP/MoS₂ heterostructures. Control over the 2DP layers reveals enhancement of the 2DP photoluminescence by two orders of magnitude in ultrathin sheets and an unexpected thickness-dependent modulation of the ultrafast excited state dynamics in the 2DP/MoS₂ heterostructure. These results provide fundamental insight into the electronic structure of 2DPs and present a route to tune emergent quantum phenomena in 2DP hybrid van der Waals heterostructures.

Graphical Abstract

INTRODUCTION

Strong interlayer electronic interactions between two-dimensional materials give rise to quantum phenomena in van der Waals (vdW) heterostructures that are of both fundamental interest and practical importance. For example, vdW heterostructures composed of semiconducting transition metal dichalcogenides (TMDCs) exhibit useful properties such as exceptionally long spin and valley polarization lifetimes,^1,2 ultrafast charge transfer between layers,^3–6 and novel exciton physics in Moiré superlattices.^7,8 Such phenomena emerge in TMDC heterostructures through the strong interlayer coupling of electronic states with similar energies. Consequently, the design of new vdW heterostructures that permit flexible control over the electronic band structure of constituent layers while maintaining strong electronic coupling at the interface is the subject of substantial research interest.

Two-dimensional polymers (2DPs), of which covalent organic frameworks (COFs) are the most synthetically diverse class, provide a compelling route to band structure design and the development of new vdW heterostructures.^9–12 2DPs are crystalline lattices formed by covalently linking planar molecular monomers into two-dimensional sheets that stack through interlayer vdW coupling. The 2DP electronic band structure can, in principle, be rationally engineered by careful selection of constituent monomers and polymerization chemistry.^13,14 With emergent properties of heterostructures intimately tied to the electronic states at the interface, the ability to tune the 2DP band structure in 2DP/TMDC vdW heterostructures would enable the design and realization of novel quantum phenomena across extended length scales with atomic precision.

Despite this promise, major challenges in synthesis, fabrication, and measurement have limited the development of semiconducting 2DP films and 2DP/TMDC heterostructures that exhibit significant interlayer electronic coupling. First, monomers designed for 2DP semiconductors should be conjugated systems with an intrinsically small band gap to promote interlayer coupling among 2DP layers and between the 2DP layer and the inorganic TMDC. Second, the 2DP must form as a highly crystalline vdW-layered film with parallel orientation for efficient interlayer electronic coupling in the heterostructure. Finally, the 2DP layer must be homogeneous across extended length scales to permit systematic optical and electronic transport studies of the heterostructure.

Recent work has demonstrated independent advances in 2DP crystallinity,^15–19 observation of topological band structures,^20–23 and monolayer synthesis.^24,25 Interfacial polymerization at solid–vacuum,^23,26 air–liquid,^25,27 and liquid–liquid^28–30 interfaces is now producing high-quality 2DP films, including those with conjugated polymerization chemistries.^31,32 However, these methods have yet to be accessible to a large number of chemical structures, often produce films that lack long-range order, and can be challenging to manipulate. Direct polymerization of 2DPs on submerged substrates has been extensively studied for a variety of chemical precursors and can permit homogeneous direct deposition, potentially promoting high-quality interfaces and strong interlayer electronic coupling. However, despite significant research effort, the observation and control of interlayer electronic coupling in 2DP and 2DP/TMDC heterostructures remains an outstanding challenge.

Here, we report that rational design and high-quality 2DP growth enables formation of layered 2DP/TMDC vdW heterostructures that exhibit strong interlayer electronic coupling and ultrafast energy transfer at the vdW interface with MoS₂ (Figure 1). We show that the high materials quality of these 2DP films permits facile manipulation and direct micromechanical exfoliation of large-area 2DP films down to few nanometers thicknesses. This enables the first thickness-dependent optical characterization of 2DP/MoS₂ heterostructures, which reveals enhancement of the 2DP’s photoluminescence efficiency by over 2 orders of magnitude in ultrathin heterostructures. We further observe interlayer electronic coupling in 2DP/MoS₂ heterostructures through subpicosecond energy transfer dynamics between the TMDC and the 2DP in the vdW heterostructure. Surprisingly, we find that the rate of transfer dynamics in the heterostructure can increase by over an order of magnitude with increasing thickness of the 2DP. These results suggest that the interlayer coupling of the 2DP has a profound effect on the evolution of the excited state dynamics in 2DPs and 2DP/TMDC heterostructures.

Figure 1.

Design and synthesis of semiconducting 2DP/TMDC heterostructures. (A) Schematic of the layered TIIP 2DP (blue) on monolayer MoS₂ (light gray triangles). MoS₂ grown by chemical vapor deposition (CVD) on Al₂O₃ (dark gray substrate) appears as triangular single-crystal monolayer flakes (light gray). (B) Monomer constituents and TIIP 2DP based on pyrene and thienoisoindigo moieties. (C) Electronic band structure of TIIP with a semiconducting band gap of 1.38 eV along the M1-H1 direction. (D) Electronic structure calculations show that the TIIP valence charge density (yellow) distribution is delocalized across the unit cell. (E) Schematic representation of the direct synthesis of 2DP TIIP films on monolayer TMDCs. (i) Substrate-supported monolayer TMDC (light gray triangles) on Al₂O₃ (dark gray substrate) is submerged in an optimized solvent blend with monomers, (ii and iii) substrate-supported direct polymerization of the 2DP forms as a homogeneous, highly crystalline layered film (dark blue), (iv) optical micrograph of the resulting TIIP/MoS₂ heterostructure shows homogeneous growth of TIIP films across monolayer MoS₂. TIIP 2DP grows preferentially on MoS₂ flakes seen here in the increased film thickness on the triangular MoS₂ flakes. Gray outline identifies one heterostructure of multilayered TIIP/MoS₂. Scale bar = 5 μm.

RESULTS AND DISCUSSION

The bottom-up design of a 2DP semiconductor is challenging because selecting constituent monomers requires simultaneous consideration of their electronic coupling, crystal lattice symmetry, and synthetic viability.³³ We addressed this through selection of an electron-rich pyrene building block and an electron-deficient thienoisoindigo linker with molecular orbital energy levels comparable to that of the semiconducting TMDCs.^22,33–35 We applied first-principles electronic structure calculations to several candidate structures (SI.I) and evaluated both the electronic structure and the synthetic viability to obtain a target 2DP (TIIP). TIIP is synthesized by condensing a tetrafunctionalized D_2h symmetric pyrene (tetrakis(4-aminophenyl)pyrene, TAPPy) with a bifunctional thienoisoindigo (N,N′-dibutyl-6,6′-diformylthienoisoindigo) (Figure 1B and SI.V–VI), which forms a layered 2D crystal with lattice constant a₁ = a₂ = 2.9 nm. Our electronic structure calculations (Figure 1C and SI.II) predict that TIIP is a semiconductor in its bulk form with an indirect band gap of 1.38 eV. Calculations also predict that the charge density at the top of the TIIP valence band is delocalized across the unit cell (Figure 1D). Notably, the intralayer lattice constant of 2DPs (2.9 nm) will be nearly 10 times larger than the interlayer (π–π) spacing (3.5 Å), suggesting that the behavior of electrons in 2DP semiconductors could be dominated by interlayer coupling rather than intralayer coupling dynamics.

Although much of the interest in semiconducting 2DPs and vdW heterostructures is focused on the potential for device applications, the vast majority of semiconducting 2DPs are synthesized as microcrystalline powders and it remains a challenge to obtain homogeneous thin films with high materials quality.^36,37 To address this, we developed an optimized solvothermal synthesis that permits the direct growth of highly crystalline and oriented TIIP films directly on sapphire and monolayer TMDC substrates (Figure 1E and SI.XIV). To promote homogeneous and crystalline film growth, we selected conditions that minimized the homogeneous formation of powder precipitates while still allowing for heterogeneous nucleation at the desired interface and confirmed the resulting structures by Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and surface area analyses (SI.VI–VIII).³⁸ The optimized solvothermal synthesis was highly reproducible and amenable to a variety of substrates. Across substrates, this synthesis generated the highest quality TIIP films on monolayer TMDCs, where the film exhibits homogeneous preferential growth in both crystallinity and thickness (SI.IX and SI.XIV). This observation is consistent with reports of preferential 2DP growth on graphene³⁹ and hexagonal boron nitride⁴⁰ and suggests that this synthesis provides a generalizable route to directly form strong interfaces between high-quality semiconducting 2DP films and monolayer TMDCs.

The resulting TIIP 2DP formed robust, homogeneous, and crystalline films, as observed through optical microscopy, transmission electron microscopy (TEM), X-ray scattering, and atomic force microscopy (AFM) (Figure 2). Optical micrographs show homogeneous large-area film growth on both sapphire (Al₂O₃) substrates and monolayer MoS₂ (Figure 1E). Grazing incidence wide-angle X-ray scattering (GIWAXS) exhibits sharp diffraction peaks at 0.21, 0.31, 0.43, and 1.76 Å⁻¹ corresponding to the 100, 110, 200, and 001 Bragg diffraction features (Figure 2A and 2B). These features correspond to lattice vectors of a₁ = a₂ = 29.8 Å and c = 3.5 Å and are in good agreement with a simulated orthorhombic 2DP structure (Figure 2B, black curve, and SI.VII) and the calculated TIIP structure (SI.II). Analysis of the angular dependence of the scattering intensity in the two-dimensional GIWAXS patterns shows that in-plane diffraction features are confined to the Q_xy axis and out-of-plane diffraction features are tightly confined to the Q_z axis. This strong radial anisotropy in the scattering intensity confirms that the TIIP 2DP crystal domains lie oriented parallel to the substrate. FTIR spectra of the TIIP films exhibit resonances consistent with a high degree of imine polymerization as well as a marked absence of resonances corresponding to oxidized species or unreacted constituent monomers (SI.VIII). Comparison of ¹³C NMR of TIIP 2DP with its constituent starting materials and a model compound further indicates formation of the imine linkage (SI.VIII). Finally, TIIP 2DP was prepared as freestanding films on TEM grids using our all-dry film transfer method (SI.XI), which enabled direct imaging of the 2DP lattice at many film positions across the grid (Figure 2C–E and SI.XII). The Fourier-transform of the real space image confirms the orthorhombic symmetry of the TIIP 2D lattice and spacings consistent with the dimensions of the monomer subunits. Collectively, these results indicate that the TIIP 2DP achieves a prerequisite for electronically coupled 2DP/TMDC heterostructures: polymerization into large-area, homogeneous, highly crystalline, vdW-layered films that orient parallel to the substrate and form heterostructures of exceptionally high quality.

Figure 2.

Structural characterization of TIIP 2DP films. (A) GIWAXS pattern from TIIP films confirm TIIP forms highly crystalline domains oriented parallel to the substrate. (B) Radial integration of the 2D GIWAXS (blue) and the simulated scattering pattern (black) indicate lattice constants a = 2.9 nm and c = 3.5 Å, consistent with theory. (C) Schematic of freestanding TIIP films (blue) transferred to a TEM grid. (Right) Optical micrograph of the TIIP film (blue) transferred to a TEM grid. Scale bar = 5 μm. (D) HR-TEM image of the TIIP film resolves the orthorhombic lattice. (E) FFT of the image in D resolves lattice symmetry.

The synthesis of homogeneous crystalline vdW-layered films enabled us to probe the predicted low band gap and semiconducting electronic structure of the TIIP film. We characterized the electrical transport properties of the TIIP film using both prepatterned bottom contacts and large-area top contacts developed for transport on 2DP films (Figure 3A and SI.X). Across devices, we observe reproducible conductivities in the TIIP film of σ = (3.5 ± 0.7) × 10⁻⁵ S/m from the top contact geometry and σ = (2.5 ± 0.8) × 10⁻⁵ S/m from the bottom contact geometry, which is among the highest intrinsic electrical conductivity reported in 2D COFs (Figure 3B).^41–45 The optical band gap of the TIIP film can be determined through optical absorption measurements on sapphire substrates (Figure 3C), which shows an onset of optical absorption at 1.6 eV. The absorption onset energy of the 2DP film is red shifted by 300 meV from that of the thienoisoindigo monomer and by 100 meV from that of an imine-containing model compound (SI.V Figure S9). The decrease of the optical gaps in the extended TIIP structures reflect the hybridization of the constituent monomers. In the TIIP/MoS₂ heterostructure, we observe additional absorption resonances corresponding to the MoS₂ A- and B-excitons (SI.XIII).⁴ The low-energy optical gap of the TIIP film is indeed comparable to that of MoS₂, which would potentially enable charge and energy transfer processes in TIIP/MoS₂ heterostructures. Consistent with our theoretical results, these observations validate the theory-driven approach to designing semiconducting 2DPs.

Figure 3.

Electrical and optical characterization of TIIP 2DP films. (A) Schematic of a patterned TIIP device. (Inset) Optical micrograph of TIIP film (blue) with lithographically patterned Au top contacts (yellow). Scale bar = 50 μm. (B) Semiconducting electrical transport of TIIP films. I–V data of films exhibit an intrinsic conductivity of σ ≈ 3.5 × 10⁻⁵ S/m. (C) Low band gap absorption of TIIP film, model compound, and monomers. Optical band gap decreases in the extended TIIP film (dark blue) from that of the constituent monomers, reflecting the hybridization of the electronic states in the extended lattice.

Enabled by the synthesis of highly crystalline and oriented vdW films, we extended techniques from all-dry micromechanical manipulation of inorganic 2D materials to exfoliate the bulk TIIP films down to a few nanometers (Figure 4). Like semiconducting TMDCs, the 2DP layers are held in vertical alignment through relatively weak van der Waals forces. When the layered crystal is oriented parallel to the substrate, covalently bound sheets can, in principle, be separated by interrupting the interlayer van der Waals interactions. Conventionally, 2DPs are challenging to exfoliate or have been limited to liquid exfoliation due to their synthesis as polycrystalline powders, lack of a preferred orientation, or substantial intersheet cross-linking defects.^46–49 In contrast, the highly crystalline synthesis and oriented stacking in the TIIP 2DP films permits precise dry mechanical exfoliation of the 2DP TIIP film (Figure 4A). We exfoliated multiple TIIP layers from the bulk substrate-supported heterostructure (Figure 4B) using a polyethylene terephthalate (PET) stamp^50,51 controlled by a three-axis micromanipulation translation stage (SI.XI). A single stamp exfoliation simultaneously removes layers from adjacent heterostructures leaving few-layered 2DP/TMDC heterostructures on the substrate (Figure 4C). AFM topography indicates that exfoliated heterostructures range from ~2.5 to 10 nm and confirms that ultrathin TIIP films are continuous, uniform, and exhibit subnanometer surface roughness across the entire heterostructure area, which is free of bubbles or nanoscale impurities (SI.IX).

Figure 4.

Exfoliation of TIIP/MoS₂heterostructures and thickness-dependent luminescence. (A) Schematic of the dry exfoliation of layered TIIP films. PET stamp is positioned above the TIIP/MoS₂ heterostructure. Using micromechanical stamp exfoliation, the vdW-layered TIIP films can be exfoliated down to few-nanometer thick sheets. (B) (Top) AFM topography of bulk layered TIIP/MoS₂ heterostructures. TIIP film covers both monolayer MoS₂ and the Al₂O₃ substrate but grows preferentially on the MoS₂. (Bottom) AFM height profile of >120 nm bulk heterostructure. Scale bar = 2 μm. (C) (Top) AFM topography of exfoliated TIIP/MoS₂ heterostructures. Topographies trace the height from the exfoliated TIIP film to the bare sapphire substrate exposed in the exfoliation. (Bottom) AFM height profile of the heterostructure exfoliated to <4 nm. Scale bar = 2 μm. (D) PL spectra at 77 K for varying TIIP film thicknesses ranging from 2.5 to >120 nm. λ_exc = 2.33 eV. Spectra are normalized by the absorbed laser power. Bulk (>120 nm, dark blue) TIIP is magnified by 25× for visual clarity.

Exfoliation of TIIP 2DP sheets reveals a striking thickness dependence in the photoluminescence (PL) spectra (normalized by absorbed laser power, Figure 4D). The PL spectra (at 77 K, 2.33 eV excitation) exhibit a significant blue shift between the bulk and the ultrathin TIIP films: two weak and broad emission peaks centered at ~1.4 and ~1.6 eV are present in the bulk film, while a single resonance at 1.75 eV dominates the emission of the ultrathin film. In addition, the bulk TIIP film shows a very low PL quantum efficiency, consistent with our calculations that bulk TIIP has an indirect band gap. In contrast, the PL quantum efficiency increases by over 2 orders of magnitude in the few nanometer TIIP film.

The electronic structure of TIIP provides insight into the layer-dependent PL of the TIIP 2DP. In particular, the calculated valence band in TIIP 2DP has an in-plane bandwidth of 50 meV but an out-of-plane bandwidth of 400 meV along the stacking direction. This strong out-of-plane dispersion indicates that the electronic bands in TIIP can exhibit a strong thickness dependence, as observed in the enhancement of the PL. The strong enhancement in PL efficiency from ultrathin TIIP films is also reminiscent of the behavior in 2D semiconducting TMDCs, where the PL efficiency is greatly enhanced in monolayers due to an indirect-to-direct band gap transition.^3,4 However, the electronic structures of 2DPs exhibit unique properties relative to their inorganic counterparts, and the exact mechanism of layer-dependent PL emission in 2DPs requires further investigation. For example, in contrast to the TMDCs, the intralayer lattice constants of 2DPs, such as TIIP, are nearly an order of magnitude larger than the interlayer (π–π) spacing. The strong out-of-plane dispersion and relatively small in-plane bandwidth is one consequence of this feature and renders the electron interlayer coupling stronger than the electron intralayer coupling in such 2DPs.

The oriented synthesis and exfoliation of 2DP films in MoS₂ heterostructures offer a new degree-of-freedom to explore previously inaccessible interlayer coupling in semiconducting 2DPs. We use two independent methods to probe the ultrafast energy transfer dynamics between ultrathin TIIP and MoS₂ layers in the TIIP/MoS₂ heterostructure: photoluminescence excitation (PLE) spectroscopy and photoluminescence (PL) quenching (Figure 5). In PLE, we monitor the emission from TIIP films as the excitation photon energy is swept across the energy range spanning the MoS₂ A- and B-exciton resonances. The resulting 2D PLE spectra of ultrathin TIIP/MoS₂ heterostructures expose two bright features where the emission of the TIIP has been enhanced at excitation energies of 1.9 and 2.1 eV (Figure 5A). While the TIIP absorption is relatively flat over this regime, these energies directly coincide with the well-known A- and B-exciton absorption of MoS₂ (SI.XIII). The enhancement of TIIP emission upon MoS₂ excitation provides direct evidence of an ultrafast energy transfer process from the MoS₂ layer to the TIIP layer through electronic coupling in the heterostructure.

Figure 5.

Interlayer electronic coupling in 2DP TIIP/MoS₂heterostructures. (A) Two-dimensional PLE spectra of TIIP in ultrathin heterostructures at 77 K. Color scale represents the normalized emission intensity. (B) Integrated PLE from TIIP (blue) and heterostructure absorption (black). Enhancement of TIIP emission upon MoS₂ excitation reveals an ultrafast transfer process from MoS₂ to TIIP through interlayer electronic coupling in the heterostructure. (C) Quenching of MoS₂ PL in the TIIP/MoS₂ heterostructure can be tuned by TIIP thickness, suggesting that interlayer dynamics can depend strongly on the thickness of the 2D TIIP layer.

The efficiency of this energy transfer can be quantitatively determined by comparing the PLE spectrum (Figure 5B, blue curve) to the absorption spectrum (Figure 5B, black curve). In the absorption spectrum, the A-exciton resonance of MoS₂ is much stronger than the broad TIIP absorption background with a resonance-to-background ratio of ~300%. In contrast, the MoS₂ A-exciton resonance shows only a ~60% enhancement over the background in the PLE spectrum, indicating that excitation of the MoS₂ A-exciton can contribute to the TIIP PL emission but does not contribute as efficiently as direct excitation of the TIIP layers. We can therefore estimate that the energy transfer efficiency—the fraction of the optical absorption in MoS₂ that leads to TIIP excitation through energy transfer—is limited to about 20%.

A second and complementary estimation of the energy transfer efficiency can be obtained from the quenching of the MoS₂ emission due to the ultrafast energy transfer process. Figure 5C shows the PL emission from the MoS₂ A-exciton in bare MoS₂ (orange), the ultrathin TIIP/MoS₂ heterostructure (green), and the bulk TIIP/MoS₂ heterostructure (blue). In the ultrathin TIIP/MoS₂ heterostructure (green), emission from the monolayer MoS₂ A-exciton resonance (1.9 eV), prominent in isolation, is quenched by ~15% in the ultrathin heterostructure. This degree of quenching corresponds to an energy transfer efficiency of 15% and is comparable to the value estimated independently from PLE spectroscopy. In contrast, the A-exciton emission in the bulk TIIP/MoS₂ heterostructure (blue) is strongly quenched and exhibits an energy transfer efficiency as high as 85%. Reproducible across numerous devices and in good agreement with the estimation from PLE spectroscopy, these results demonstrate that the excited state dynamics in TIIP/MoS₂ heterostructures can depend strongly on the thickness of the 2D TIIP layer.

The rate of energy transfer across the TIIP/MoS₂ heterostructure can be estimated from the respective energy transfer efficiencies. The energy transfer efficiency, η, is set by the competition between the exciton decay rate within MoS₂ (γ_MoS2) and the energy transfer rate to TIIP (γ_transfer) and is described by $\eta =\frac{{\gamma }_{\text{transfer}}}{{\gamma }_{\text{MoS2}}+{\gamma }_{\text{transfer}}}$. Studies of CVD-grown MoS₂ show that the MoS₂ total decay rate, γ_MoS2, is on the order of 1 ps⁻¹,⁵² consistent with our time-resolved PL measurements of the exciton lifetime of the CVD-grown MoS₂, limited by the instrument response time of the streak camera (~2 ps). Thus, γ_MoS2 ≈ 1 ps⁻¹ provides a useful bound for the MoS₂ total decay rate, and the energy transfer rate can be estimated from the experimentally realized energy transfer efficiency for different 2DP thicknesses. Bulk TIIP/MoS₂ exhibits a high energy transfer efficiency of 85%, corresponding to an ultrafast energy transfer rate on the order of 6 ps⁻¹. In contrast, the transfer efficiency in ultrathin TIIP/MoS₂ at 15% is relatively low and corresponds to a dramatically reduced transfer rate of 0.2 ps⁻¹. Consequently, these results suggest that the process of energy transfer in the heterostructure slows by more than an order of magnitude with decreasing 2DP TIIP thickness. The strongly thickness-dependent energy transfer rates in TIIP/MoS₂ heterostructures are quite unexpected. These observations suggest that the excited state dynamics in the coupled 2DP/TMDC heterostructure may be linked to the intrinsic interlayer coupling of the 2DP, underscoring robust opportunities to design emergent phenomena in hybrid 2DP/TMDC heterostructures.

CONCLUSION

In conclusion, we demonstrate that through high-quality layered 2DP growth on monolayer TMDCs, it is possible to engineer electronically coupled hybrid vdW heterostructures that reveal unexpected ultrafast excited state dynamics. We deterministically design the electronic band structure of TIIP and demonstrate growth of oriented and crystalline semiconducting TIIP films and TIIP/MoS₂ heterostructures of extremely high quality. We confirm structural characterization in both real and reciprocal space (GIWAXS, TEM, and AFM) and low band gap electronic characterization through optical absorption and semiconducting electrical transport.

These advances enabled direct exfoliation of 2DP films and the first thickness-dependent study of hybrid 2DP/TMDC heterostructures, which offers a new degree of freedom to explore in low-dimensional 2DP physics. Thickness-dependent measurements reveal that 2DP PL efficiency can increase by over 2 orders of magnitude in few nanometer TIIP films and suggest consequences of the lattice dimensions that may be broadly general to 2DPs. Surprisingly, the subpicosecond energy transfer rate in the TIIP/MoS₂ heterostructure is also modulated by TIIP layer number, which indicates that the interlayer coupling of the 2DP is intrinsically linked to the excited state dynamics of the coupled heterostructure. This coordinated approach to band design and realization of electronically coupled semiconducting TIIP/MoS₂ heterostructures demonstrates that 2DPs represent a powerful route to engineering novel 2D heterostructures for optoelectronic applications. Finally, extending this work to 2DPs containing topologically nontrivial band structures could open rich opportunities for the design and control of strongly correlated electronic states^33,53 in hybrid vdW heterostructures.