EPR of X-ray-irradiated [(CH3)2NH2][Zn(HCOO)3] hybrid perovskite
Abstract
Incorporating paramagnetic metal ions into hybrid materials is a standard practice to enable electron paramagnetic resonance (EPR) studies of phase transitions and dynamics. Yet, the inclusion of foreign ions in the lattice can significantly distort the local structure, resulting in the inaccurate understanding of the material properties. Less invasive paramagnetic defects can be formed by high energy irradiation. Here, we report a continuous-wave (CW) EPR study of X-ray-irradiated [(CH3)2NH2][Zn(HCOO)3] hybrid perovskite, which possesses a structural phase transition at ~160 K. The CW EPR spectrum reveals a rhombic g-tensor with no clearly resolved hyperfine splittings. Assisted by the DFT calculations, we assign the spectrum to a radical species on the formate linker. The temperature dependence of the measured gzz component reveals a broad anomaly in a broad temperature range close to the phase transition point, which we relate to the change in the dynamics of a formate linker.
