Novel antisolvent synthesis and investigations of structural, optical and electrical properties of lead-free Cs 2 AgBiBr 6

Abstract We study the effect of antisolvent engineering on the geometrical, electrical, optical and ionic properties of lead-free halide perovskite Cs 2 AgBiBr 6 , targeting optoelectronic applications. Three antisolvents, ethanol, ethyl methyl ketone (EMK), and a 1:1 mixture of ethanol and EMK, were used to recrystallize Cs 2 AgBiBr 6 colloidal particles via a reprecipitation method. Structural analysis through x-ray diffraction confirms the formation of the cubic phase of Cs 2 AgBiBr 6 in all antisolvents without impurity. UV–vis spectroscopy showed absorption edges shifting with antisolvents, reflecting bandgap tuning. Elemental analysis by x-ray photoelectron spectroscopy confirmed stoichiometric composition, and Fourier-transform infrared and Raman studies verified the structural integrity. Conductivity analysis revealed that EMK-treated Cs 2 AgBiBr 6 exhibits high conductivity and offers high activation energy for ion migration compared to ethanol and mixed antisolvent. Impedance spectroscopy showed that the sample recrystallized in the EMK solvent exhibits the lowest bulk resistance compared to the other antisolvents, indicating more efficient charge carrier transport. Overall, the EMK antisolvent system demonstrated the most balanced improvement in optical and electrical properties. We have also explored optoelectronic properties of EMK crystallized Cs 2 AgBiBr 6 using density functional theory. These experimental and theoretical findings highlight the crucial role of the solvent environment in tailoring the properties of Cs 2 AgBiBr 6 , rendering them promising candidates for eco-friendly, optoelectronic applications.