Strain gradient induced anomalous thermal conduction behavior in CsPbI3

YL Pang and CX Cui and YX Xue and JW Jiang, INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER, 169, 109682 (2025).

DOI: 10.1016/j.icheatmasstransfer.2025.109682

All-inorganic perovskite CsPbI3 inevitably undergoes thermal mismatch strain with a spatially non-uniform distribution during fabrication. However, the impact of such strain on thermal transport and related properties remains unclear. Motivated by this issue, we investigate the thermal conduction of CsPbI3 under compressive strain with a spatial gradient and compare it with that under uniform compressive strain. We find that the compressive strain gradient leads to anomalous thermal transport behavior, whereas uniform compression enhances thermal transport. Specifically, thermal conductivity remains almost unchanged under moderate strain but gradually decreases with increasing strain, eventually exhibiting a reduction of nearly 40%. The stability in the moderate strain range results from a balance between compression- enhanced high-frequency vibrations and gradient-induced mismatch of vibrational modes. The reduction at larger strain originates from dislocation defects that hinder phonon transport. These findings reveal the overlooked role of strain gradients in thermal transport and provide additional theoretical insights into strain effects in perovskites.

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