Polymer-Free Films of Inorganic Halide Perovskite Nanocrystals as UV-to-White Color-Conversion Layers in LEDs

Lead(II) bromide (PbBr2, 99.999% trace metals basis), lead(II) iodide (PbI2, 99.999% trace metals basis), cesium carbonate (Cs2CO3, reagentPlus, 99%), iodine (I2, 99.99%), hydrochloric acid (HCl, ACS reagent, ≥ 37%), hydriodic acid (HI, 57wt.% in H2O), hydrobromic acid (HBr, 48 wt. % in H2O, ≥99.99%), indium(III) acetate (In(Ac)3, 99.99%), copper(I) iodide (CuI, purum, ≥99.5%), 1-dodecanethiol (DDT, ≥98%), zinc(II) stearate (Zn(StA)2, technical grade), 1-octadecene (ODE, technical grade, 90%), oleylamine (OLAM, 70%) and oleic acid (OA, 90%), and chloroform (CHCl3, >99%) were purchased from Sigma-Aldrich. Cadmium(II) oxide (CdO, >99%), selenium powder (Se, >99%) and sulfur powder (S, 99%), trioctylphosphine (TOP, 90%) and trioctylphosphine oxide (TOPO, 99%) were purchased from STREM Chemicals. Octadecylphosphonic acid (ODPA, >99%) was purchased from PCI Synthesis. Toluene (TOL, anhydrous, 99.8%), methanol (MeOH, >99%), ethanol (EtOH, >99%), and isopropanol (IPrOH, >99%) were bought from Carlo Erba reagents. All chemicals were used without any further purification, except for OLAM, OA, and ODE, which were degassed at 100 °C for 2 h in vacuum.