Revealing the enhanced crystalline quality mechanism of perovskites produced by microwave-assisted synthesis: toward the fabrications in a fully ambient air environment

Abstract

The conventional stirring method (CSM) in a nitrogen-controlled glovebox has been widely used to synthesize the Cs/MA/FA precursor solution. However, it involves a long preparation time and limits the fabrication conditions in an ambient environment, hindering their potential for high-end applications and environmental stability. Herein, we systematically developed a fast and efficient microwave-assisted synthesis (MAS) method to produce a high-quality and stable triple cation perovskite (Cs0.1(MA0.17FA0.83)0.9Pb(Br0.17I0.83)3) solution and fabricated a device in ambient conditions. The superiority of using the MAS compared to CSM is manifested by comparing the improvements in crystal nucleation, enhanced optical properties, and its excellent stability with time, owing to the homogeneous heating of the precursor solution during the synthesis method. The MAS-prepared perovskite films showed anomalous photoluminescence blue-shift and linewidth broadening with increasing temperature, emphasizing the unique properties of the triple cation perovskite fabricated. These results were later interpreted and fitted to discuss the induced lattice thermal expansion, structural phase transition, and electron–phonon interactions that highlighted the enhanced crystal quality from the MAS-perovskite films. Considering the substantial fabrication parameters and conditions, the structural and optical stability of the MAS-perovskite films were maintained over time during exposure to air and ultraviolet light, even without encapsulation. To further elucidate the crystal quality improvements from using the MAS-perovskite solution, the fabrication of perovskite transistors in a completely ambient environment resulted in a 10-fold increase in electron carrier mobility compared to the CSM-perovskite devices. The developed synthesis method has contributed significant advantages to enhance the structural and environmental stability of perovskites, making a promising approach for larger-scale and more efficient future optoelectronic device applications.