Purification of Perovskite Quantum Dots Using the Drop Casting of a Polar Solvent for Memory Devices with Improved Performance and Stability

The evolution of optoelectronic devices has been significantly influenced by the development of metal halide perovskites, particularly all-inorganic cesium lead halide perovskites (CsPbX₃, where X is a halide). These materials have several advantageous properties, including long carrier diffusion lengths, high and broad absorption spectra, tunable bandgaps, high carrier mobility, and low-temperature fabrication processes. These qualities make them highly suitable for applications in light-emitting diodes and solar cells. However, the practical application of perovskite quantum dots (QDs) synthesized through the hot-injection method, stabilized by hydrophobic alkyl ligands, is hindered by decreased charge transport characteristics and quantum efficiency due to the insulative nature of the ligands. Innovations to overcome these limitations have included using shorter halide ion pair ligands, such as didodecyl dimethylammonium bromide, and optimizing purification processes to enhance charge injection and maintain stability. We introduced a novel approach for surface ligand engineering through a methanol-based washing process applied during spin-coating, effectively removing excess ligands and residual solvents, and potentially offering a path toward the fabrication of high-performance, low-voltage memory devices using perovskite QDs. This method not only simplifies the purification process but also preserves the photoluminescence, colloidal stability, and structural integrity essential for scalable optoelectronic applications.