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HL: Fachverband Halbleiterphysik
HL 35: Perovskite and photovoltaics II (joint session HL/CPP)
HL 35.7: Vortrag
Dienstag, 17. März 2020, 15:30–15:45, POT 251
Structural and optical properties of defect-engineered organic-inorganic halide perovskites — •Chang-Ming Jiang1, Wen-Yu Cheng1, Michael Ehrenreich2, Gregor Kieslich2, and Ian Sharp1 — 1Walter Schottky Institut, Technische Universität München — 2Fakultät für Chemie, Technische Universität München
Incorporating large organic cations into the ABX3 hybrid perovskite is known to yield the so-called 'hollowed perovskite' structure. To accommodate the oversized cation onto the A-site, certain concentrations of B2+ cation and X- anion vacancies form. The presence of these point defects and associated dangling bonds are expected to affect the electronic properties, charge carrier dynamics, and phase stability. In the case of FASnI3, incorporation of ethylenediammonium (en2+) cations enlarges the optical bandgap and significantly improves the photovoltaic efficiency and stability. In this work, we aim at understanding the composition-dependent optical properties and relative phase stability in the defect-engineered (en)MAPbI3 system. Thin films with tunable bandgaps from 1.60-1.85 eV are fabricated, and the non-radiative recombination pathways associated with intentionally added point defects are studied by time-resolved PL techniques. Additionally, by measuring temperature dependence of PL, we find that both the orthorhombic-to-tetragonal and tetragonal-to-cubic phase transition temperatures are affected by the extent of large organic cation incorporation. This work sheds light on the interactions between organic cations and the inorganic lattice and provides insights into the defect tolerance in hybrid halide perovskite semiconductors.