Christian Camus, Nasim Rezaei-Hartmann, Adrian, Enno Malguth, Claudine Groß, Kolja Haberland, LayTec AG, Berlin, Germany
Organic–inorganic halide perovskites have emerged as a key materials platform for next-generation optoelectronic devices, including photovoltaics, LEDs, and photodetectors. Despite rapid efficiency progress, perovskite processing remains highly sensitive to deposition conditions, often relying on empirically optimized “black-box” recipes and limited reproducibility with limited real-time feedback. Optical in-situ metrology offers a powerful route to overcome these limitations by providing continuous, non-destructive insight into film formation, chemistry, and optoelectronic properties.
This review presentation summarizes recent advances in optical in-situ monitoring of perovskite thin-film formation using spectral reflectance and photoluminescence (PL) techniques across a range of deposition methods, including spin-coating, slot-die coating, and vacuum co-evaporation. We demonstrate how time-resolved reflectance enables quantitative tracking of wet and dry film thickness, drying dynamics, refractive index evolution, and surface roughness, thereby providing a detailed fingerprint of perovskite formation kinetics. Particular emphasis is placed on the role of surface roughness, which leads to characteristic attenuation and disappearance of interference features and must be carefully considered in optical data interpretation.
Furthermore, we show how the combination of reflectance and in-situ PL spectroscopy enables real-time assessment of bandgap formation, compositional changes, and the detection of secondary or parasitic phases during growth. Correlative analysis of absorption edges and PL peak positions allows identification of phase purity and deviations from targeted perovskite compositions. By consolidating results from multiple processing routes, this contribution highlights the versatility of optical in-situ metrology as a universal diagnostic and control tool for perovskite electronics.
Overall, this review illustrates how optical in-situ reflectance and PL measurements transform perovskite processing from a trial-and-error approach into a data-driven, controllable manufacturing process, accelerating both fundamental understanding and industrial scalability.