We use time- and angle-resolved photoemission spectroscopy (TR-ARPES) combined with density functional theory to investigate ultrafast carrier dynamics in low-symmetry layered semiconducting PdSe2. The indirect bandgap is determined to be 0.55~eV. Following photoexcitation above this gap, we resolve a valence band shift and broadening, both lasting less than a picosecond, consistent with bandgap renormalization and carrier scattering, indicative of strong many-body interactions. Subsequently, hot carriers populate the conduction band minimum and are captured by defect states. A surface photovoltage (SPV) of ∼ 67~meV emerges, persisting for over 50~ps, driven by defect-assisted charge separation. The formation of native vacancies, promoted by the low-symmetry lattice, likely gives rise to the mid-gap states responsible for this long-lived SPV response. Detailed analysis of TR-ARPES spectra disentangles the contributions of bandgap renormalization, carrier scattering, defect states, and SPV. These findings establish PdSe2 as a prototypical layered quantum material exhibiting exotic photoresponses on ultrafast timescales.
@article{arxiv.2510.26011,
title = {Photoinduced Electronic Band Dynamics and Defect-mediated Surface Potential Evolution in PdSe$_2$},
author = {Omar Abdul-Aziz and Manuel Tuniz and Wibke Bronsch and Fulvio Parmigiani and Federico Cilento and Daniel Wolverson and Charles J. Sayers and Giulio Cerullo and Claudia Dallera and Ettore Carpene and Paul H. M. van Loosdrecht and Hamoon Hedayat},
journal= {arXiv preprint arXiv:2510.26011},
year = {2025}
}