Extrinsic Bulk Photovoltaic Effect from Asymmetric Defect Scattering

Zixun Wang; Andrew M. Rappe

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arXiv · 2610.25029

Extrinsic Bulk Photovoltaic Effect from Asymmetric Defect Scattering

Zixun Wang·Andrew M. Rappe

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Abstract

The extrinsic bulk photovoltaic effect from asymmetric electron-defect scattering can make an important contribution to the total photocurrent and is highly diagnostic of defect type. We present an ab initio Boltzmann framework combining optical excitation with electron-phonon and symmetric and skew electron-defect scattering, and we apply it to monolayer GeS. Because the defects that generate the current also relax the anisotropy that sustains it, the response peaks at a finite defect fraction. Within the scattering-limited model, cooling to $0$~K shifts the peak position toward lower defect fractions and yields a maximum enhancement of more than six orders of magnitude at fixed defect fraction. At selected low-temperature defect fractions, the total extrinsic current can exceed the intrinsic shift current by more than an order of magnitude, so that the defect fraction itself becomes a tunable parameter.

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Zixun Wang, Andrew M. Rappe. 2026-10-18. Extrinsic Bulk Photovoltaic Effect from Asymmetric Defect Scattering. https://arxiv.org/abs/2610.25029

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