Colloidal Perovskite Nanocrystals for Optoelectronics*

Light-emitting diodes (LEDs) and lasers are part of our everyday life as they are commonly used in a variety of electronic systems.
LEDs have become the most efficient source of light (with an efficiency around 50%), thanks to a continuous development of novel materials since the first observation of electroluminescence in 1907. On the other hand, lasers are fundamental components of communication systems and sensors and discovery of new materials has allowed to tune their properties based on the require application.
Here, I will discuss how colloidal semiconductor nanocrystals possess ideal properties for application in these two types of light-sources. In fact, this class of materials has seen extensive application in optoelectronic devices thanks to their versatile synthesis that allows tuning of their optoelectronic properties.
I will focus on perovskite colloidal nanocrystals with structure APbX3 (where A = Cesium, Methylammonium or Formamidinium and X = Chlorine, Iodine or Bromine) showing how their high photoluminescence quantum yield, colour tuneability and defect tolerant structure can be exploited in LEDs and lasers. Importantly, perovskite nanocrystals present a surface functionalized with organic ligands that guarantee colloidal stability. Yet, the surface ligands can be substituted or further functionalized to improve functional stability as well as control the optoelectronic properties of the material. Similarly, the chemical composition can be tuned on-demand via anion and cation exchange reactions (e.g. substituting Pb with Cd or Br with I) opening an additional tailoring pathway. Both surface and composition modifications can be employed to improve the performance of LEDs or Lasers and I will present here some of the latest findings of our research group.