The class of hybrid perovskites regained great attention since the applicability of methylammonium lead iodide (MAPI) as an active material for solar cells was discovered a few years ago.[1] The transition from 3D systems including MAPI to 2D systems opens up further possible optoelectronic applications such as lasing or solid-state lighting due their inherent quantum well structure, which results from the formation of excitions with large binding energies.[2] The high structural flexibility of hybrid perovskites obtained by a systematic choice of the A-site cation composition makes them a versatile platform to adjust the optoelectronic properties according to specific demands.[3] The benzimidazolium lead halide perovskites series including (C7H7N2)2PbCl4, (C7H7N2)2PbBr4, (C7H7N2)2PbI4, and (C7H7N2)PbI3 is a good candidate for investigating the effect of dimensionality and the choice of the halide on the band gap. Besides a comprehensive characterization of the above mentioned compounds we confirmed that a decrease in band gap can be achieved by going from chloride to bromide and to iodide and by increasing the dimensionality from 1D to 2D.[4] Dimensionality also plays an important role when finding strategies to overcome MAPI's intrinsic water sensitivity, as 2D systems typically show higher moisture resistivity.[5] In addition, the choice of a more hydrophobic organic cation could also contribute to enhance the system's stability towards water. Both approaches were taken into account when synthesizing the compound (FC2H4NH3)2PbCl4, which was characterized by DSC, PXRD, 1H, 13C and 207Pb solid-state NMR spectroscopy, UV-vis absorption spectroscopy and time-resolved photoluminescence measurements.[6]

New 2D hybrid perovskite systems for optoelectronic applications

253rd National Meeting (2017)

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