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HL: Fachverband Halbleiterphysik

HL 7: Poster I

HL 7.33: Poster

Monday, March 27, 2023, 13:00–15:00, P2/EG

Monitoring Phase Transitions in (Hot-)Pressed FAPbI₃ Films by In-Situ Reflection Measurements — •Lorenz Kiel¹, Christina Witt¹, Konstantin Schötz¹, Nico Leupold², Ralf Moos², Anna Köhler¹, and Fabian Panzer¹ — ¹Soft Matter Optoelectronics, University of Bayreuth, Bayreuth 95440, Germany — ²Department of Functional Materials, University of Bayreuth, Bayreuth 95440, Germany

In recent years, a remarkable increase in efficiencies of halide perovskite-based solar cells has been achieved. Record cells on laboratory scale, realized with the perovskite formamidinium lead iodide (FAPbI₃), are now competing with established silicon devices.[1] However, phase stability of FAPbI₃ is still challenging as the photoactive black α-phase is prone to degrade in the inactive yellow δ-phase or intermediate orange and red phases.[2, 3] To address this issue, we evaluate the temperature and pressure dependence of occurring phase transitions using in-situ reflection measurements during (hot-)pressing δ-FAPbI₃ powder, and analyze associated strain in the resulting thick films. We show that for our powder based thick films the phase transitions occur at significantly lower pressure and temperature compared to literature reports. The correlation of these parameters with resulting film properties like film morphology suggests strain to be decisive for the phase transition and phase stability.

[1] Jeong et al. Nature 2021, 592.

[2] Cordero et al. Nanomaterials 2021, 11.

[3] Cordero et al. J. Phys. Chem. C 2020, 124.