LAUSR

The emerging broad range of applications of the glow discharge optical emission spectroscopy (GD‐OES) technique in the field of perovskite solar cells (PSCs) research is reviewed. It can provide a large palette of information by easily and quickly tracking the depth distribution of light to heavy elements. After a discussion of the advantages and the limitations of the technique and a comparison with other analytical techniques, how GD‐OES is employed to give structural information on perovskite solar cells is shown. GD‐OES has allowed the full perovskite film formation process investigation, from the initial precursor layers containing soaking and complexed solvent to the final crystallized 3D perovskite layers. The A‐site elemental cations distribution is followed‐up during the film formation. In addition, this technique gives a deep insight into the action mechanism of additives and their effects on the film formation. It provides fruitful information on optimized light absorbing layers and on the selective contact layers which ensure the charge transport in PSCs. It allows to directly visualize halide ions migration and their blocking by ad‐hoc chemical engineering and to study the films and PSCs ageing. GD‐OES opens new perspectives to explain the final performances of the devices.