Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 7: Focus Session: When theory meets experiment: Hybrid halide perovskites for applications beyond solar I (joint session HL/CPP)

HL 7.4: Talk

Monday, March 16, 2020, 11:15–11:30, POT 251

Optoelectronic properties of lead-free double-perovskites from first principles — •Raisa I. Biega¹, Marina R. Filip^2,3, Linn Leppert¹, and Jeffrey B. Neaton^2,3,4 — ¹Institute of Physics, University of Bayreuth, Bayreuth, Germany — ²Department of Physics, University of California, Berkeley, USA — ³Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, USA — ⁴Kavli Energy NanoSciences Institute, Berkeley, USA

Power conversion efficiencies of single junction solar cells with lead-based halide perovskite absorbers have exceeded 25%. However, stability concerns have stimulated efforts for finding substitutes with similar optoelectronic properties, i.e., small band gaps, low effective masses and small exciton binding energies. Double perovskites containing alternating mono- and trivalent metal cations have emerged as one such alternative. Here we present first principles calculations of the electronic structure and excited states of the double perovskites Cs2AgBX6 (B=Bi, Sb and X=Br, Cl). We use density functional theory and ab initio Green’s function-based many-body perturbation theory within the GW and Bethe-Salpeter equation approach to calculate band structures and absorption spectra of these materials. Our results provide insights into the nature of optical excitations and suitability for photovoltaic and other light harvesting applications.

We acknowledge computational resources provided by NERSC, a DOE Office of Science User Facility supported by the U.S. Department of Energy and financial support by the DFG Programs SFB840 and GRK1640.