Journal Article 2D materials machine learning Raman spectroscopy Research Support, Non-U.S. Gov't SnSe aerogels black phosphorus chemical vapor deposition conjugated microporous polymers deep learning electrical properties electrochemical exfoliation ferroelectric domains ferroelectric stacking freeze drying group-IV monochalcogenides hydrogen-free exfoliation in-plane ferroelectric materials material characterization molybdenum molybdenum disulfide optical microscopy photodetectors photoluminescence physical vapor deposition second-harmonic generation semiconductor alloys sorption tunable bandgaps