Speaker
Description
Metal-halide perovskites are promising materials for next-generation photovoltaic and optoelectronic devices. Yet, their performance remains strongly affected by structural defects that induce unfavorable charge-carrier recombination, thereby decreasing the overall device efficiency. Vacuum vapor deposition is a scalable, solvent-free fabrication route with precise control over film thickness and composition. However, further optimization of this process requires a detailed understanding of perovskite nucleation, crystal growth, morphology evolution, and defect formation during deposition.
This work focuses on the real-time investigation of halide perovskite thin-film formation during vacuum deposition using in situ grazing-incidence X-ray scattering and photoluminescence spectroscopy. Such a combination of techniques during perovskite deposition reveals the formation of nanoscale perovskite islands, their coalescence, and subsequent steady vertical layer growth.
The observed nonmonotonic PL evolution—an initial intensity increase followed by pronounced quenching—does not simply follow the increasing perovskite phase volume, but instead reflects the formation of defect states and enhancement of nonradiative recombination. Furthermore, in situ X-ray scattering enables tracking of lattice strain during growth. The transition from compressive to tensile strain marks the onset of grain coalescence and coincides with PL quenching, directly linking growth stage, strain, and defect formation. Finally, we show how this understanding can be used for targeted defect passivation: introducing potassium salts during perovskite deposition produces an immediate enhancement of PL intensity, indicating efficient suppression of nonradiative recombination and defect passivation without substantial modification of the perovskite crystallographic structure.
These results demonstrate that combining X-ray scattering with optical spectroscopy provides a powerful feedback platform for understanding vapor-deposited perovskite film growth, guiding additive selection, defect passivation, and scalable fabrication strategies for high-performance perovskite solar cells.
