Near-Infrared Optical Response and Carrier Dynamics for High Photoconversion in Tellurene br

Materials for applications in solar cells require acombination of features including an appropriate band gap andlong relaxation times for photoexcited hot carriers. On the basis ofab initiomany-body perturbation theory, including the spin-orbitinteraction, we investigate the photocarrier generation anddynamics in alpha-tellurene. We show that photoexcited electronsare mainly generated in the near-infrared range, starting at 0.89 eVand forming excitons that are strongly bound, compared to its bulkcounterpart, with a binding energy of 0.31 eV. We also explore therole of the electron-phonon interaction,finding that the electronicstates in thefirst conduction band minimum couples weakly withphonons, yielding longer hot electron lifetimes (up to 70 fs) andmean free paths up to 37 nm. We also show that the extraction of hot holes may result in a challenging task as these carriers possesssub-3 nm mean free paths. Wefinally estimate that 1-nm-thick alpha-Te provides a short-circuit current density of 6.7 mA/cm2and amaximum power conversion efficiency of 4.4%, which highlights its potential for efficient photovoltaic device development.