Researchers crack the code for building better perovskite nanocrystals
Scientists have discovered that the chemical choice made during nanocrystal purification—not just polarity—determines whether the material survives and performs well. The finding offers manufacturers a new framework for selecting solvents that could speed development of brighter, more stable light-emitting displays and other optoelectronic devices.
Originaltitel: Stronger Lewis Base Antisolvents Improve Perovskite Nanocrystal Stability
Lead-halide perovskite nanocrystals (NCs) have gained attention for optoelectronics, but careful selection of the antisolvent used for purification is essential to achieve high monodispersity and yield while minimizing surface damage. Current understanding indicates that this requires lowering the relative polarity of the antisolvent, yet high-polarity antisolvents are widely used for purification, as we confirm through data mining. We show that polarity alone is insufficient for antisolvent selection by comparing ethyl acetate and acetonitrile for CsPbI3 NC purification. Despite its higher polarity, acetonitrile yields improved colloidal stability compared to ethyl acetate. Using 1H NMR, FTIR, and XPS measurements, alongside DFT calculations, we demonstrate that acetonitrile acts as a stronger Lewis base, binding to and passivating the NC surface. Coordination of acetonitrile to the perovskite NC surface enhances stability and improves their performance in light-emitting diodes. These findings establish a mechanistic framework for antisolvent selection to realize bright and stable halide perovskite NCs.