(Invited) Nanoscale Morphology Control in Halide Perovskite/Polymer Composites for Printed LEDs and Beyond

Recently, astounding optoelectronic properties have been discovered in halide perovskites (perovskites). Such materials have a general ABX3 chemical formula, in which A is a cesium (Cs+) or an aliphatic ammonium (RNH3 +) cation, B is a divalent Pb2+ or Sn2+ cation and X is an anion such as Cl-, Br- or I-. Their crystal structures resemble the one commonly found in BaTiO3. The halide perovskites can be processed like polymeric semiconductor materials using solution based processes; and may be coated into large area thin films on arbitrary substrates; they may also be crystallized into three-dimensional periodic structures and behavior like conventional inorganic semiconductors including the superior charge transportation properties. In this talk, our recent work of developing perovskite/polymer composites towards the realization of fully printable LEDs will be presented. The perovskite/polymer composites possesses all the remarkable optoelectronic characteristics of pure perovskites. For instance, we have demonstrated their use for blue, green and red LEDs. In addition the device efficiencies exceeded those of pure perovskite LEDs. The perovskite/polymer composites have shown advantages in improving the processability and quality of the perovskite thin films; and enhancing the structural stability of the perovskites especially at high humid fabrication and service environments. By embedding the perovskite crystals inside a polymer matrix, the perovskites can be less toxic and more environmentally benign compared to pure perovskite. At the end of the talk, other potential applications of perovskite/polymer composites will be briefly discussed.