How fast do defects migrate in halide perovskites: insights from on-the-fly machine-learned force fields

Abstract

The migration of defects plays an important role in the stability of halide perovskites. It is challenging to study defect migration with experiments or conventional computer simulations. The former lacks...

Imperfections are not 0 K: free energy of point defects in crystals

“…The significant cost of these calculations would justify training a model for the defective systems, which can be achieved via fine-tuning ( e.g. training a model for the bulk and then re-training it for relevant configurations of the defective systems 157 ). We highlight that further work is still required to determine the optimal approach for defect MLFF training, particularly regarding the number and diversity of defect configurations required to achieve sufficient accuracies.…”

Ion Migration in Lead-Halide Perovskites: Cation Matters

“…The authors found that the nonradiative recombination is accelerated due to the enhanced nonadiabatic coupling and the quantum coherence time is longer as ion migration occurs. Moreover, Tao and co-workers employed the machine learning force field to identify the qualitative trends in migration rates for different defect types and chemical compositions . Liu and co-workers investigated the key factors affecting the efficiency and stability using machine learning and established a mathematical model to predict efficiency based on the fluorescence lifetime and bandgap .…”

“…Moreover, Tao and co-workers employed the machine learning force field to identify the qualitative trends in migration rates for different defect types and chemical compositions. 100 Liu and co-workers investigated the key factors affecting the efficiency and stability using machine learning and established a mathematical model to predict efficiency based on the fluorescence lifetime and bandgap. 101 Interactions between migrating anions and stationary cations within perovskites have been discussed in several reports.…”

Kinetic Process with Anti-Frenkel Disorder in a CsPbI3 Perovskite

“… Ø ⇌ V X • + X i ′ This is much higher than the Schottky disorder and thus has received less attention in previous studies. However, research has indicated that aF becomes predominant in MAPbI 3 above 290 K. , The additional aF can probably decompose into I i and V I , leading to a fast ion diffusion , and providing additional charge carrier traps . Nevertheless, the detailed pathways of aF creation and I i diffusion are still in question, especially in the all-inorganic CsPbI 3 perovskite.…”