Ligand-free synthesis of organic–inorganic perovskite and all-inorganic lead-free double perovskite nanocrystals by femtosecond laser pulses

Perovskite materials are at the forefront of modern materials science due to their exceptional structural, electronic, and optical properties. The controlled fabrication of perovskite nanostructures is crucial for enhancing their performance, stability, and scalability, directly impacting their applications in optoelectronic and sensing technologies. Here, we present a ligand-free and solvent-free approach to synthesize perovskite nanocrystals (NCs) with average sizes up to 100 nm, using femtosecond pulsed laser ablation (PLA) in ambient air without additional liquid media. We demonstrate this method for both organic–inorganic (methylamino lead) hybrid perovskites (MAPbX 3 , X = Cl, Br, I) and fully inorganic lead-free double perovskites (Cs 2 AgBiX 6 , X = Cl, Br), achieving high-purity NCs without stabilizing ligands — a critical advancement over conventional chemical synthesis methods. By tailoring laser parameters, we systematically elucidate the influence of perovskite composition (halide type, organic vs. inorganic cation, single vs. double perovskite structure) on the ablation process and the resulting nanocrystal properties. Transmission electron microscopy and X-ray diffraction confirm the preservation of crystallinity, with MAPbX 3 forming cubic NCs ( ∼ 90 nm) and Cs 2 AgBiX 6 forming smaller, rounded NCs ( ∼ 10 − 15 nm ). Photoluminescence spectroscopy reveals pronounced size-dependent spectral shifts (17–40 nm) due to quantum confinement, particularly for Br- and I-containing perovskites. Time-resolved photoluminescence measurements further reveal shortened decay times in laser-fabricated NCs compared to bulk crystals, indicating enhanced surface- and defect-assisted recombination. This solvent-free, scalable, and versatile PLA approach not only provides direct access to high-purity, ligand-free perovskite NCs with tunable optical properties but also represents a significant advance in the fabrication of nanostructures, enabling the further exploration of perovskite-based optoelectronic and quantum applications. • Femtosecond pulsed laser ablation enables one-step synthesis of ligand-free perovskite nanocrystals. • Nanocrystal morphology and size distribution highly depend on perovskite composition. • Laser-fabricated perovskite nanocrystals show preserved crystallinity with no additional phases. • Ligand-free nanocrystals exhibit size-dependent photoluminescence behavior.