Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 18: Perovskite and Hybrid Photovolatics

HL 18.5: Talk

Tuesday, March 13, 2018, 10:30–10:45, EW 203

Cation substitution reduces non-radiative bimolecular losses in hybrid lead-halide perovskites — •Sascha Feldmann, Jasmine P. H. Rivett, Tudor H. Thomas, Michael Saliba, and Felix Deschler — University of Cambridge, JJ Thomson Avenue, CB3 0HE Cambridge, UK

Tailored monovalent cation substitution in mixed-cation hybrid perovskites enables solar cell efficiencies beyond 20% and enhanced stability. Here, we use transient absorption and photoluminescence spectroscopy to study the effect of cation substitution on the carrier recombination dynamics in Rbx(Csy(MAzFA1-z)1-y)1-xPb(I0.83Br0.17)3 (MA=methylammonium, FA=formamidinium) hybrid perovskite thin-films. We perform a detailed analysis of the recombination dynamics, from which we separate radiative and non-radiative recombination pathways. We find that careful tuning of the cation composition leads to a reduction in trap-assisted non-radiative recombination channels, which supports enhanced lifetimes and high luminescence yields. Unexpectedly, we further observe the reduction of a non-radiative bimolecular recombination channel, particularly upon inclusion of formamidinium. Using Raman and X-ray diffraction techniques, we study the effect of cation substitution on lattice order. We find that formamidinium inclusion, aided through the presence of Rb and Cs during fabrication, leads to a reduction of the tetragonal distortion, and an increased rigidity of the lattice. We attribute the enhanced luminescence yields to reduced defect formation through carrier trapping due to the reduced lattice disorder.