Fig. 1. Characterization of twisted 2D organic-inorganic heterostructures. (a) Band structure of a 2D pentacene-MoS2 HS calculated using DFT. (b) Schematic diagram of the HS illustrates the twist angle (θ), which is defined as the deviation between the b-axis of pentacene and the armchair direction of MoS2. (c) Calculated interlayer spacings of HS at θ=0 and 30 deg. It shows a lower interlayer spacing at θ=30deg (∼2.70Å) compared with 0 deg (∼2.92Å). (d) Calculated interlayer spacing as a function of θ from 0 to 60 deg, displaying a minimum (∼2.70Å) at θ=30deg. (e) SAED pattern for 2D pentacene, confirming the high crystallinity. (f) PL spectra of 1L MoS2, 2D pentacene single crystal, and HS at room temperature. The inset is the optical image of the HS. The scale bar is 20μm. It shows that the interface between the 2D pentacene and MoS2 is flat and clean. (g) Schematic of band alignment for HS, showing type II characteristics. (h) PL quenching factor (η, left) from various analyzed heterostructures with different twist angles at room temperature, along with the charge transfer efficiency (γ, right) at various twist angles. (i) Blueshift of excitons (upper) and their FWHM (bottom) from HS as a function of twist angles.

Fig. 2. Twist angle–dependent couplings. (a) Three-level energy diagram including the exciton (A), trion (T), and ground state (G). (b) Twist-dependent PL intensity ratio of the trion to exciton (IT/IA, upper) and doping level (n, bottom left) and Fermi level (EF, bottom right) as a function of twist angle at 300 K. (c) PL intensity of the exciton and trion, their total contribution (left), and dependence on gate voltage (VG) of the drain-source current (right). (d) Peak energy difference between excitons and trions (EA−ET, x-axis) and the Fermi level (right y-axis) of isolated 1L MoS2 as a function of different VG. (e) PL quenching factor (η, left) and charge transfer efficiency (γ, right) of HS as a function of temperature. (f) Coupling strength (S) as a function of twist angle.

Fig. 3. Electrical control of interlayer couplings. (a) and (b) Orbital resolved band structure of HS with a bias voltage of 0.003 e (a) and −0.003e (b), respectively. (c) PDOS of HS calculated at V_G > 0 (upper) and V_G < 0 (bottom). (d) Schematic illustration of HS MOS device. (e) PL quenching factor (η, left) and charge transfer efficiency (γ, right) of HS as a function of gate voltage. The inset is the band alignment of HS under V_G < 0 and V_G > 0.

Fig. 4. Interlayer relaxations under horizontal electric fields. (a) PL images at various VG of HS. Scale bar: 5μm. (b) Exciton diffusion lengths (LD) of HS with gate voltages ranging from −50 to 50 V. (c) Schematic for trion and exciton diffusion in HS at V_G < 0 and V_G > 0. (d)–(f) Scanning photocurrent image measured under −0.5V (d), 0 V (e), and 0.2 V bias (f). The inset is the optical image of the device. The olive frame is the scanning area, and the white frame is the heterostructure region. Scale bar: 10μm. (g) Schematic band diagram of the 2D pentacene-MoS2 device at reverse bias; the arrow shows the direction of the horizontal electric field. (h) Schematic band diagram at zero bias. (i) Schematic band diagram at forward bias. (j) Schematic of the process contributing to the charge transfers.