Structural and thermodynamic limits of layer thickness in 2D halide perovskites

• DOI: 10.1073/pnas.1811006115
• Publication Date: 2018-12-18T21:15:13Z
• Authors: Chan Myae Myae Soe; G. P. Nagabhushana; Radha Shivaramaiah; Hsinhan Tsai; Wanyi Nie; Jean-Christophe B...; Ferdinand Melkonyan; Duyen H. Cao; Boubacar Traoré; Laurent Pedesseau; Mikaël Kepenekian; Claudine Katan; Jacky Even; Tobin J. Marks; Alexandra Navrotsky; Aditya D. Mohite; Constantinos C. S...; Mercouri G. Kanat...
• Keywords: Crystal (programming language)

In the fast-evolving field of halide perovskite semiconductors, 2D perovskites (A')2(A) n-1M n X3n+1 [where A = Cs+, CH3NH3+, HC(NH2)2+; A' ammonium cation acting as spacer; M Ge2+, Sn2+, Pb2+; and X Cl-, Br-, I-] have recently made a critical entry. The value defines thickness layers, which controls optical electronic properties. demonstrated preliminary optoelectronic device lifetime superior to their 3D counterparts. They also attracted fundamental interest solution-processed quantum wells with structural physical properties tunable via chemical composition, notably by defining layer thickness. higher members (n > 5) not been documented, there are important scientific questions underlying limits for To develop utilize these materials in technology, it is imperative understand thermodynamic stability, synthetic limitations, derived structure-function relationships. We report effective synthesis highest iodide n-members yet, namely (CH3(CH2)2NH3)2(CH3NH3)5Pb6I19 6) (CH3(CH2)2NH3)2(CH3NH3)6Pb7I22 7), confirm crystal structure single-crystal X-ray diffraction, provide indirect evidence "(CH3(CH2)2NH3)2(CH3NH3)8Pb9I28" ("n 9"). Direct HCl solution calorimetric measurements show compounds 7 unfavorable enthalpies formation (ΔHf), suggesting homologs be challenging. Finally, we n-dependent solar cell efficiency range 9-12.6% n-members, highlighting strong promise high-performance devices.