This study aimed to find a universal parameter for measuring the layer number of 2D material flakes using optical imaging. The study analyzed the intensity ratio and intensity slopes of mechanically exfoliated flakes using various imaging systems and found that the intensity slope (for RGB) and intensity ratio (for RAW) could be used to determine layer numbers accurately. The study also developed a MATLAB-based graphical user interface (GUI) to facilitate the analysis of slope values and layer confirmation. This approach could have broad applications in materials science and beyond.

This study explores the moiré physics of nearly 0⁰ twisted heterostructures by optimizing the sample preparation technique and measuring photoluminescence (PL) emission. In such heterostructures, interlayer excitons (ILXs) experience a slowly varying potential landscape called moiré potential. ILXs can get trapped in such potential minima, resulting in an ultra-long lifetime and single photon emission. We use the dry transfer technique to stack mechanically exfoliated MoSe2 and WSe2 MLs. Photoluminescence (PL) response for the MoSe2/WSe2 HS is measured at 4K. Optical excitation in a type II HS (such as MoSe2/WSe2) is followed by ultrafast charge transfer and the formation of interlayer excitons. PL response in the 900 nm to 1000 nm range corresponds to interlayer exciton (ILX) emission. We have also built a Time Resolved PL setup which will be used to study the dynamics of these interlayer excitons.