Organolead halide perovskites of general APbX3 (A= organic ammonium cation, X = halide anion) formula combine useful properties of both organic and inorganic materials, such as plastic mechanical properties (organic material) and good electronic mobility (inorganic material).1,2
These hybrid organic-inorganic perovskites are of great interest in photovoltaic devices and as luminescent materials for light-emitting devices. Their photoluminescence (PL) spectrum can be modified via controlled changes on their stoichiometry. There are quite a few studies exploring the performance of these perovskites, in particular of those with the CH3NH3PbX3 (X= halide) stoichiometry, with respect to their optical gain, quantum yield, or as components of optical devises, among other features. In spite of that, there is a demand for enhancing their emissive properties to be used in efficient luminescent devices. In addition, there are concerns on their stability and degradation which affect their performance.
Crystalline nm-sized CH3NH3PbX3 nanoparticles have recently been prepared via a non-template strategy3,4 and they yield colorful, highly luminescent, and stable colloidal solutions. Thus, we have recently demonstrated that CH3NH3PbBr3 nanoparticles can be efficiently prepared by fine-tuning the molar ratios of all the components, which either formed part of the framework (CH3NH3Br and PbBr2) or acted as the organic capping. The method consisted in the induced precipitation of the nanoparticles from a mixture of all the components. These nanoparticles exhibited a high luminescence (83% quantum yield, emission lifetime ca. 600 ns) and photostability. These perovskites preserve their emissive properties in the solid state, which makes them promising for use in light emitting devices. This non-template strategy proved useful for the preparation of perovskite nanomaterials with other stoichiometry.5
Other interesting strategy to prepare CH3NH3PbBr3 perovskite nanomaterial with high luminescence (up to 93% quantum yield, emission lifetime ca. 18 ns) is that of ligand-assisted re-precipitation (LARP) technique.6,7 The synthetic yield of the perovskite nanoparticles by this method is limited due to the formation of bulk material by-products along with the desired nanoparticles, further decreasing with the increase of the synthesis temperature.
In this presentation the preparation methods of colloidal organolead halide nanoparticles will be discussed
1. D. B. Mitzi. In Progress in Inorganic Chemistry; John Wiley&Sons, Inc.: 1999; Vol. 48, p 1.
2. M. Grätzel et al., Nature 2013, 499, 316-319.
3. L. C. Schmidt, A. Pertegás, S. González-Carrero, O. Malinkiewicz, S. Agouram, G. Mínguez Espallargas, H. J. Bolink, R. E. Galian, J. Pérez-Prieto, J. Am. Chem. Soc. 2014, 136, 850−853.
4. S. González-Carrero, R. E. Galian, J. Pérez-Prieto J. Mater. Chem. A, 2015,3, 9187-9193.
5. S. González-Carrero, G. Mínguez Espallargas, Raquel E. Galian, J. Pérez-Prieto J. Mater. Chem. A, 2015, 3, 14039–14045
6. F. Zhang, H. Zhong, C. Chen, XG Wu, X Hu , H. Huang, J. Han, B. Zou, Y. Dong ACS Nano, 2015, 4, 4533.
7. H. Huang , A. S. Susha , S. V. Kershaw , T. F. Hung , A. L. Rogach Adv. Sci. 2015, 1500194.