Unique Optical Properties of Methylammonium Lead Iodide Nanocrystals Below the Bulk Tetragonal-Orthorhombic Phase Transition.

Title Unique Optical Properties of Methylammonium Lead Iodide Nanocrystals Below the Bulk Tetragonal-Orthorhombic Phase Transition.
Authors B.T. Diroll; P. Guo; R.D. Schaller
Journal Nano Lett
DOI 10.1021/acs.nanolett.7b04099
Abstract

Methylammonium (MA) and formamidinium (FA) lead halides are widely studied for their potential as low-cost, high-performance optoelectronic materials. Here, we present measurements of visible and IR absorption, steady state, and time-resolved photoluminescence from 300 K to cryogenic temperatures. Whereas FAPbI3 nanocrystals (NCs) are found to behave in a very similar manner to reported bulk behavior, colloidal nanocrystals of MAPbI3 show a departure from the low-temperature optical behavior of the bulk material. Using photoluminescence, visible and infrared absorption measurements, we demonstrate that unlike single crystals and polycrystalline films, NCs of MAPbI3 do not undergo optical changes associated with the bulk tetragonal-to-orthorhombic phase transition, which occurs near 160 K. We find no evidence of frozen organic cation rotation to as low as 80 K or altered exciton binding energy to as low as 3 K in MAPbI3 NCs. Similar results are obtained in MAPbI3 NCs ranging from 20 to over 100 nm and in morphologies including cubes and plates. Colloidal MAPbI3 NCs therefore offer a window into the properties of the solar-relevant, room-temperature phase of MAPbI3 at temperatures inaccessible with single crystals or polycrystalline samples. Exploiting this phenomenon, these measurements reveal the existence of an optically-passive photoexcited state close to the band edge and persistent slow Auger recombination at low temperature.

Citation B.T. Diroll; P. Guo; R.D. Schaller.Unique Optical Properties of Methylammonium Lead Iodide Nanocrystals Below the Bulk Tetragonal-Orthorhombic Phase Transition.. Nano Lett. 2018. doi:10.1021/acs.nanolett.7b04099

Related Elements

Iodine

See more Iodine products. Iodine (atomic symbol: I, atomic number: 53) is a Block P, Group 17, Period 5 element with an atomic radius of 126.90447. The number of electrons in each of Iodine's shells is 2, 8, 18, 18, 7 and its electron configuration is [Kr] 4d10 5s2 5p5. The iodine atom has a radius of 140 pm and a Van der Waals radius of 198 pm. In its elemental form, iodine has a lustrous metallic gray appearance as a solid and a violet appearance as a gas or liquid solution. Elemental IodineIodine forms compounds with many elements, but is less active than the other halogens. It dissolves readily in chloroform, carbon tetrachloride, or carbon disulfide. Iodine compounds are important in organic chemistry and very useful in the field of medicine. Iodine was discovered and first isolated by Bernard Courtois in 1811. The name Iodine is derived from the Greek word "iodes" meaning violet.

Lead

Lead Bohr ModelSee more Lead products. Lead (atomic symbol: Pb, atomic number: 82) is a Block P, Group 14, Period 6 element with an atomic radius of 207.2. The number of electrons in each of Lead's shells is [2, 8, 18, 32, 18, 4] and its electron configuration is [Xe] 4f14 5d10 6s2 6p2. The lead atom has a radius of 175 pm and a Van der Waals radius of 202 pm. In its elemental form, lead has a metallic gray appearance. Lead occurs naturally as a mixture of four stable isotopes: 204Pb (1.48%), 206Pb (23.6%), 207Pb (22.6%), and 208Pb (52.3%). Elemental LeadLead is obtained mainly from galena (PbS) by a roasting process. Anglesite, cerussite, and minim are other common lead containing minerals. Lead does occur as a free element in nature, but it is rare. It is a dense, soft metal that is very resistant to corrosion and poorly conductive compared to other metals. Its density and low melting point make it useful in applications such as electrolysis and industrial materials.

Nitrogen

See more Nitrogen products. Nitrogen is a Block P, Group 15, Period 2 element. Its electron configuration is [He]2s22p3. Nitrogen is an odorless, tasteless, colorless and mostly inert gas. It is the seventh most abundant element in the universe and it constitutes 78.09% (by volume) of Earth's atmosphere. Nitrogen was discovered by Daniel Rutherford in 1772.

Related Forms & Applications