Wafer-Scale Van der Waals Assembly of Free-Standing Near Atom Thickness Hetero-Membranes for Flexible Photo-Detectors

Heterogeneous integrations of functionally and chemically distinct materials have been explored to develop promising building blocks for opto-electronic device applications. Recently, the Van der Waals (vdW)-assembly of near atom thickness materials has provided excellent opportunities beyond what has been previously been difficult to realize. However, its up-to-date demonstrations remain far from achieving the scalability and versatility demanded for practical device applications, that is, the integration is generally demonstrated with intrinsically layered 2D materials of very small lateral dimensions. Herein, the large centimeter-scale vdW assembly of two different materials with structurally, chemically, and functionally distinct properties, that is, 2D platinum ditelluride (PtTe2) metallic multilayers and non-layered 3D semiconducting platinum sulfide (PtS) are reported. Both materials are precisely delaminated from their growth wafers inside water and are subsequently integrated on unconventional substrates of desired functionalities. The large-area vdW-assembled 2D/3D PtTe2/PtS hetero-materials on flexible substrates exhibit an excellent photodetection in a spectral range of visible-to-near infrared (NIR) wavelength, which is well preserved under severe mechanical deformation. This study paves the way for exploring large-area flexible opto-electronic devices solely based on near atom thickness materials.