High Members of the 2D Ruddlesden-Popper Halide Perovskites
High Members of the 2D Ruddlesden-Popper Halide Perovskites: Synthesis, Optical Properties, and Solar Cells of (CH3(CH2)3NH3)2(CH3NH3)4Pb5I16
Constantinos C. Stoumpos, Chan Myae Myae Soe, Hsinhan Tsai, Wanyi Nie, Jean-Christophe Blancon, Duyen H. Cao, Fangze Liu, Boubacar Traoré, Claudine Katan, Jacky Even, Aditya D. Mohite, Mercouri G. Kanatzidis
DOI: 10.1016/j.chempr.2017.02.004.
First published online 9 Mar 2017
Paper on publisher's website
Paper in open access repository
We present the fifth member (n = 5) of the Ruddlesden-Popper (CH3(CH2)3NH3)2(CH3NH3)n-1PbnI3n+1 family, which we successfully synthesized in high yield and purity. Phase purity could be clearly determined from its X-ray powder diffraction patterns, which feature the (0k0) Bragg reflections at low 2θ angles. The obtained pure n = 5 compound was confirmed to be a direct band-gap semiconductor with Eg = 1.83 eV. The direct nature of the band gap is supported by density functional theory calculations. Intense photoluminescence was observed at room temperature at 678 nm arising from the band edge of the material. High-quality thin films can be prepared by the hot-casting method from solutions with a pure-phase compound as a precursor. The planar solar cells fabricated with n = 5 thin films demonstrate excellent power-conversion efficiency of 8.71% with an impressive open-circuit voltage of ∼1 V. Our results point to the use of layered perovskites with higher n numbers and pure chemical composition.
DFT calculations performed at the Institut des Sciences Chimiques de Rennes received funding from GOTSolar.
Image: Ruddlesden-Popper (RP) perovskites are cutting-edge materials in the field of hybrid halide perovskite semiconductors as second-generation systems for optoelectronic devices. (CH3(CH2)3NH3)2(CH3NH3)4Pb5I16 represents the fifth (n = 5) member of a homologous RP perovskite series. The orthorhombic material has a direct band gap Eg of 1.83 eV and exhibits room-temperature photoluminescence at 678 nm. Density functional theory calculations indicate that the compound has broad electronic bands with light effective masses for electron and hole carriers, comparable with those of the CH3NH3PbI3 (n = ∞) perovskite, resulting in high charge-carrier mobility required for planar opto-electronic device applications. We thus demonstrate highly stable planar solar cells fabricated with this material as a light absorber with a promising efficiency of 8.71%.