A Universal Approach toward Light-Responsive Two-Dimensional Electronics: Chemically Tailored Hybrid van der Waals Heterostructures.

Stimuli-responsive hybrid van der Waals heterostructures (vdWHs), composed of organic molecular switches superimposed on inorganic 2D materials (2DMs), can combine the outstanding physical properties of the latter components with the virtually infinite variety of tunable functionality of molecules, thereby offering an efficient protocol for the development of high-performance multifunctional materials and devices. The use of light as a remote control to modulate the properties of semiconducting 2DMs when interfaced with photochromic molecules suffers from both the limitation associated with the persistent photoconductivity characterizing the 2DMs and the finite thermal stability of the photochromic molecule in its different states. Here, we have devised a universal approach toward the fabrication of optically switchable electronic devices comprising a few nanometers thick azobenzene (AZO) layer physisorbed on 2D semiconductors supported on a trap-free polymer dielectric. The joint effect of the improved 2D/dielectric interface, the molecule's light-modulated dipolar doping, and the high thermal stability of cis-AZO offers the highest control over the reversible and efficient charge carrier tuning in 2D semiconductors with a preserved high performance in 2D field-effect transistors, as quantified in terms of carrier mobility and Ion/ Ioff ratio. The device has the potential to operate as an optical memory with four current levels and long retention time (>15 h). Furthermore, by using a CMOS-compatible micropatterning process, the photoswitchable resistor-diode transition has been achieved on hybrid lateral heterojunction devices. Our approach is of general applicability toward the generation of high-performance hybrid vdWHs for the emergence of functional and responsive devices.