SKM 2023 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 25: Perovskite and photovoltaics II (joint session HL/CPP)

HL 25.10: Talk

Wednesday, March 29, 2023, 12:30–12:45, JAN 0027

Characterization of optoelectronic properties of CsSnI3 perovskite thin film as a function of chemical composition. — •Fatima Akhundova, Hannes Hempel, Marin Rusu, Elif Hüsam, Marcus Bär, and Thomas Unold — Helmholtz-Zentrum Berlin

The performance of lead-based halide perovskites as a next generation solar cell rises every year, however toxicity of Pb is a major obstacle for commercialization. Tin is the immediate substitute for Pb in perovskite crystal structure as both metals possess the same electronic configuration. However, Sn-perovskite solar cells have significantly lower efficiencies which is partially caused by poor stability of Sn(II). We report a systematic study of structural and optoelectronic properties of co-evaporated CsSnI3 thin films with regard to lateral compositional gradient. Elemental compositions are confirmed by X-ray fluorescence and X-ray photoelectron spectroscopy techniques. Grazing-incidence X-ray diffraction reveals orthorhombic gamma phase with different preferred orientation for the excess Sn and Cs content. Moreover, Cs-rich regions shows better phase stability than the Sn-rich parts which undergo a phase transition to non-perovskite phase. The optical band gap, work function, and ionization energy are measured as a function of the Cs:Sn ratio to characterize the band diagram. The photoluminescence quantum yield, the charge carrier lifetime and mobility present these properties are rather robust against changes in composition. Our work emphasizes the impact of chemical composition on optoelectronic properties of Sn-based perovskites and demonstrates agile strategy for compositional engineering in materials research.