Layered 2D alkyldiammonium lead iodide perovskites: synthesis, characterization, and use in solar cells

Abstract

The synthetic route and properties of three 2D hybrid organic/inorganic lead iodide perovskite materials are reported. The 2D perovskites were synthesized from the reaction between PbI₂ and the di-cations of 1,4-diaminobutane, 1,6-diaminohexane, and 1,8-diaminooctane. The resulting products were [NH₃(CH₂)₄NH₃]PbI₄ (BdAPbI₄), [NH₃(CH₂)₆NH₃]PbI₄ (HdAPbI₄), and [NH₃(CH₂)₈NH₃]PbI₄ (OdAPbI₄). Structural characterization shows that two dimensional perovskite structures were formed with inorganic structural planes separated by organic layers. Absorption spectra show band gaps of 2.37 eV (BdAPbI₄), 2.44 eV (HdAPbI₄), and 2.55 eV (OdAPbI₄). The 2D perovskite materials were investigated as light absorbing materials in solid state solar cells. The best performing material under moist, ambient conditions was BdAPbI₄ (1.08% efficiency), which was comparable to methylammonium Pb(II) iodide (MAPbI₃) solar cells (2.1% efficiency) manufactured and studied under analogous conditions. When compared to MAPbI₃, the 2D materials have larger band gaps and lower photoconductivity, while BdAPbI₄ based solar cells shows a comparable absorbed photon-to-current efficiency as compared to MAPbI₃ based ones.