Structures of a Complex Hydrazinium Lead Iodide, (N2H5)15Pb3I21, Possessing [Pb2I9]5−, [PbI6]4−, and I− Ions and α‐ and β‐(N2H5)PbI3. Issue 1 (4th December 2017)

• Record Type: Journal Article
• Authors: Campbell, Eric V.; Dick, Brandon; Rheingold, Arnold L.; Zhang, Chuang; Liu, Xiaojie; Vardeny, Zeev V.; Miller, Joel S.
• Is Part Of: Chemistry. Volume 24:Issue 1(2018)
• Page Start: 222
• Page End: 229
• Publication Date: 2017-12-04
• Subjects: hydrazinium -- hydrogen bonding -- lead -- perovskite -- structure elucidation; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201704356
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Photovoltaic perovskites, most notably methylammonium lead triiodide, (NH3 Me)PbI3, have recently attracted considerable attention, and based upon the modified "Goldschmidt" as well as a "revised" tolerance factors, hydrazinium should be able to occupy the same cation site as methylammonium, and form a cubic unit cell. The reaction of N2 H5 + I − with PbI2 in dimethylformamide results in three types of yellow crystals; hexagonal, needle‐like, and rod‐like, the structures of which were determined at 100 K. The hexagonal ( P 63 /m: a= 10.8906(10) Å; b= 37.845(5) Å) crystals possess isolated face‐sharing octahedral [Pb2 I9 ] 5−, [PbI6 ] 4−, and I − ions. IR spectroscopy indicates the presence of hydrogen‐bonded N2 H5 + and the composition was determined by single‐crystal X‐ray diffraction, density measurements, combustion elemental analysis, and thermogravimetric analysis to be (N2 H5 )15 Pb3 I21, which is photoluminescent at 50 K, but not at room temperature. The needle and rod crystals have an orthorhombic ( Pnma : a= 11.1385(7) Å; b= 4.4806(3) Å; c= 17.6241(11) Å) and hexagonal ( P 63 / mmc : a= 8.7386(9) Å; b= 8.2006(9) Å) unit cells, respectively, possessing the perovskite ABX3 composition of (N2 H5 )PbI3, but neither exhibits the cubic Perovskite structure type. The structures of α‐ and β‐(N2 H5 )PbI3 possess parallel ribbons of Pb2 I4 and chains of PbI2, respectively. Strong inter‐hydrazinium hydrogen bonding due to it possessing both hydrogen bonding donor and acceptor sites (unlike NH3 Me + ) appear to stabilize the observed extended ribbon motif for (N2 H5 )15 Pb3 I21 and α‐(N2 H5 )PbI3 . (N2 H5 )15 Pb3 I21 has a band‐gap‐like absorption of 2.34 eV, and both α‐ and β‐(N2 H5 )PbI3 have a 2.70 eV band‐gap‐like absorptions. Abstract : Photovoltaic Perovskites have gained considerable attention in recent years and using the 'Goldschmidt Tolerance Factor' numerous compositions can be used to form photovoltaic Perovskites. Mixing hydrazinium iodide with lead(II) iodide forms three unique crystalline materials. The results can improve computational modeling for determining compositions that will form a Perovskite.