Organic-inorganic hybrid lead iodide perovskite with zero-dipole-moment guanidinium (GA$=$[C(NH$_{2}$)$_{3}$]$^{+}$) cations: a Density Functional based analysis

Mixed organic-inorganic halide perovskites have been reported to have superior performances [1] and unique features [2, 3] when used as light harvesters in photovoltaics. Interestingly, they can undergo several assembling procedures like sensitization and thin-film architecture. The latter one has been anyway recently reported to be affected by a noticeable hysteresis in the $J-V$ curves at slow scan rate [4]. No conclusive reasons for such behaviour have been provided so far. By means of an \textit{ab-initio} campaign of calculations [5], we predict possible chemical solutions based on the replacement of the widely employed methylammonium (MA$=$CH$_{3}$NH$_{3}^{+})$ cation with cations with reduced dipole moment, thus less sensitive to any applied external bias. \\[4pt] [1] Researchers at KRICT certified PCE of 17.9{\%}.\\[0pt] [2] Xing et al., Science 342, 344 (2013); Stranks et al., Science 342, 341 (2013).\\[0pt] [3] Giorgi et al. J. Phys. Chem. Lett. 2013, 4 (24), pp 4213; J. Phys. Chem. C, 2014, 118 (23), 12176; J. Mater. Chem. A, (2014), DOI: 10.1039/c4ta05046k.\\[0pt] [4] Snaith et al., J. Phys. Chem. Lett., 2014, 5, 1511.\\[0pt] [5] www.vasp.at