Controlling Quantum Confinement in Luminescent Perovskite Nanoparticles for Optoelectronic Devices by the Addition of Water

Here, a simple method for controlling the size of the perovskite nanoparticles (PNPs) during preparation is reported. Metal halide PNPs have great potential for application in optoelectronic devices, such as light-emitting diodes, lasers, photodetectors, etc. They have exceptionally high photoluminescence quantum yields (PLQYs) and exhibit chemical tunability for versatile modifications of the perovskite structural composition, enabling the synthesis of nanoparticles with controlled size, shape, and optical properties. In this work, methylammonium lead bromide PNPs were prepared using a hygroscopic stabilizing ligand, tert-butoxycarbonyl-Lysine (tboc-Lysine). Water was used as an additive in the precursor solution, which resulted in the formation of highly mobile species and, thus, the nhancement of perovskite lattice growth. This method allowed the preparation of PNPs with controlled size between 4 and 7 nm. The quantum confinement effect led to a fine-tuned optical band gap of the nanoparticles. Increasing the amount of water added from 0 to 32 mol equiv with respect to Lead(II) bromide (PbBr2) increased the PLQY to 70% in colloidal solutions and to 87% in thin films. Therefore, because of control over the size and high luminescent yields, the above-mentioned nanoparticles are targeted for use in optoelectronic devices.