title: (CH3NH3)2Pb(SCN)2I2: a more stable structural motif for hybrid halide photovoltaics?
abstract: Hybrid halide perovskites have recently emerged as a highly efficient class of light absorbers; however, there are increasing concerns over their long-term stability. Recently, incorporation of SCN(-) has been suggested as a novel route to improving stability without negatively impacting performance. Intriguingly, despite crystallizing in a 2D layered structure, (CH3NH3)2Pb(SCN)2I2 (MAPSI) possesses an ideal band gap of 1.53 eV, close to that of the 3D connected champion hybrid perovskite absorber, CH3NH3PbI3 (MAPI). Here, we identify, using hybrid density functional theory, the origin of the smaller than expected band gap of MAPSI through a detailed comparison with the electronic structure of MAPI. Furthermore, assessment of the MAPSI structure reveals that it is thermodynamically stable with respect to phase separation, a likely source of the increased stability reported in experiment.
authors.affiliation: University College London , Kathleen Lonsdale Materials Chemistry, Department of Chemistry, 20 Gordon Street, London WC1H 0AJ, United Kingdom.|Diamond Light Source, Ltd. , Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom.
authors.forename: Alex M
authors.initials: AM
authors.lastname: Ganose
authors.affiliation: University College London , Kathleen Lonsdale Materials Chemistry, Department of Chemistry, 20 Gordon Street, London WC1H 0AJ, United Kingdom.
authors.forename: Christopher N
authors.initials: CN
authors.lastname: Savory
authors.affiliation: University College London , Kathleen Lonsdale Materials Chemistry, Department of Chemistry, 20 Gordon Street, London WC1H 0AJ, United Kingdom.|Diamond Light Source, Ltd. , Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom.
authors.forename: David O
authors.initials: DO
authors.lastname: Scanlon
keywords: MAPI; MAPSI; hybrid halide perovskite solar cells; thiocyanate (SCN)