jp8b00602_si_004.cif (12.42 kB)
Critical Comparison of FAPbX3 and MAPbX3 (X = Br and Cl): How Do They Differ?
dataset
posted on 2018-02-23, 00:00 authored by Sharada Govinda, Bhushan P. Kore, Diptikanta Swain, Akmal Hossain, Chandan De, Tayur N. Guru Row, D. D. SarmaDielectric
measurements on formamidinium lead halide perovskites,
FAPbCl3 and FAPbBr3, compared to those of MAPbCl3 and previously reported MAPbBr3, reveal the strongly
suppressed temperature dependence of dielectric constants in FA compounds
in the temperature range of approximately 140–300 K. Although
the behavior of dielectric constants of FA compounds for temperatures
<140 K resembles that of the MAPbX3 system, the absence
of any strong temperature dependence in sharp contrast to MA analogues
in the higher temperature range up to room temperature suggests that
the formamidinium (FA) dipoles are in a deep-frozen glassy state unlike
the MA dipoles that rotate nearly freely in the temperature range
relevant for any photovoltaic application. This observation is further
supported by the temperature-dependent single-crystal X-ray diffraction
(XRD) results.