Proceedings of Perovskite Thin Film Photovoltaics (ABXPV17)
Publication date: 18th December 2016
The high efficiency conversion (up-to 21.6 % [1]) of alkylammonium lead halide perovskite solar cells has attracted the attention of the scientific community in the recent years. Despite the spectacular advances in cell efficiency, many aspects of the methylammonium lead iodide (MAPbI3) are poorly understood. In particular, the origin of its colossal dielectric constant, which is amplified under illumination,[2] remains still unsettled. Additionally, it is well known that moisture affects the MAPbI3 in many ways (morphology, crystallization, etc.) and that under moisture conditions at room temperature it suffers a phase transformation into MAPbI3.H2O,[3] leading to an inclusion of water molecules inside its structure.
In this context, the goal of this work is try to obtain experimental evidence about the origin of large dielectric constant of the MAPbI3 and the role of moisture conditions.
In this work, we have measured the complex dielectric permittivity and carry out an impedance spectroscopy analysis on a pellet samples and thin films as a function of frequency (1 Hz - 1 MHz) and temperature (100 K - 350 K). Also, we have studied the influence of the moisture conditions on the dielectric and conductivity response of the MAPbI3 compound. Very interestingly, the experimental findings point out that the presence of moisture induces several changes at the values of the dielectric constant and conductivity on the MAPbI3 material at room temperature.
(1) Grätzel, M. et al. Science 2016, 354, 206-209.
(2) Bisquert, J. et al. J. Phys. Chem. Lett. 2014, 5, 2390.
(3) Barnes, P.R.F. et al. Chem. Mater. 2015, 27, 3397-3407.