title: Air-stable molecular semiconducting iodosalts for solar cell applications: Cs2SnI6 as a hole conductor.
abstract: We introduce a new class of molecular iodosalt compounds for application in next-generation solar cells. Unlike tin-based perovskite compounds CsSnI3 and CH3NH3SnI3, which have Sn in the 2+ oxidation state and must be handled in an inert atmosphere when fabricating solar cells, the Sn in the molecular iodosalt compounds is in the 4+ oxidation state, making them stable in air and moisture. As an example, we demonstrate that, using Cs2SnI6 as a hole transporter, we can successfully fabricate in air a solid-state dye-sensitized solar cell (DSSC) with a mesoporous TiO2 film. Doping Cs2SnI6 with additives helps to reduce the internal device resistance, improving cell efficiency. In this way, a Z907 DSSC delivers 4.7% of energy conversion efficiency. By using a more efficient mixture of porphyrin dyes, an efficiency near 8% with photon confinement has been achieved. This represents a significant step toward the realization of low-cost, stable, lead-free, and environmentally benign next-generation solid-state solar cells.
authors.affiliation: Department of Materials Science and Engineering, Northwestern University , Evanston, Illinois 60208, United States.
authors.forename: Byunghong
authors.initials: B
authors.lastname: Lee
authors.forename: Constantinos C
authors.initials: CC
authors.lastname: Stoumpos
authors.forename: Nanjia
authors.initials: N
authors.lastname: Zhou
authors.forename: Feng
authors.initials: F
authors.lastname: Hao
authors.forename: Christos
authors.initials: C
authors.lastname: Malliakas
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Yeh
authors.forename: Tobin J
authors.initials: TJ
authors.lastname: Marks
authors.forename: Mercouri G
authors.initials: MG
authors.lastname: Kanatzidis
authors.forename: Robert P H
authors.initials: RP
authors.lastname: Chang