$I^{-}$ Activation energy and ion migration

In $MAPb{I}_3$ several modeling studies and experimental studies have been conducted. The results is varying for the activation energy.
Formation energy: 0.1 - 0.2 eV
Migration : 0.1-0.6 eV for halide ($I^{-}$) vacancies.

The different migration path of I-.
The activation energy depends on how much lattice distortion is required during movement of the defect.

For experimental result, the value diverse. The reason:

• Small temperature range. The Arrhenius relation not clear.
• Device response can be influence by: starting position and source of the defects, diffusion and drift contribution, additional temperature formation, etc
• Measured systems commonly nanocrystalline, not a single crystal. There are ground boundaries.

Big problem:
the device to device variation was too large. The value would be depend on the exact experiment procedure.

(then what about using automation??? may be the sollution)

Source

Metal Halide Perovskites as Mixed Electronic–Ionic Conductors: Challenges and Opportunities—From Hysteresis to Memristivity

Linked notes