2D TMD and perovskite materials have attracted intensive research interests due to their unique electrooptical properties. Detailed understanding structural information and layer-layer interaction will help greatly in tailoring their properties for applications. We use Raman and PL spectroscopic/imaging techniques to study few-layer 2D TMD samples and perovskites. Our results show that layer-layer coupling and stacking sequence significantly affect spin-orbit coupling in 2D samples. High pressure study and ab initio calculations are used to elucidate the 4000 times PL enhancement in CH3NH3PbBr3. The proposed indirect to direct band gap transition is further confirmed using time resolved PL measurements.