One clear advantage of our proposed approach is experimental simplicity. Commercially available UV-vis spectrophotometers have absorbance resolution ≤ 0.001, which is an order of magnitude lower than exciton absorbance peak values of ultrathin TMD semiconductors (Fig. ). However, large area, defect-free samples are required for benchtop absorbance measurements. Ensemble-average measurements in a benchtop instrument report on the average behaviour of the entire sample in the light path, which could include defects and pinholes in the material as shown in Fig. and Fig. . We argue the advantages and disadvantages of the optical approach proposed herein are similar to the popular Mott-Schottky method for bulk semiconductor/electrolyte interfaces; Mott-Schottky data is to acquire but can be difficult to interpret. Future experimental and theoretical work is needed to adapt the proposed approach for a wide range of 2D materials and electrochemical cell geometries and components.