Regensburg 2025 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 45: Perovskite and Photovoltaics II (joint session HL/KFM)

HL 45.10: Talk

Thursday, March 20, 2025, 12:00–12:15, H13

On the Nature of Light Induced Defects in MAPI Thin Films: Long Pulses in TrPL — •Maxim Simmonds and Eva Unger — Kekuléstraße 5, 12489 Berlin, Germany

Metal-halide perovskite (MHP) semiconductors are highly relevant candidates for the fabrication of next generation solar cells but suffer from instability under continuous irradiation. This has been shown with a non-constant steady state PL during illumination. In order to better understand the evolution of recombination mechanisms at play, we usetime resolved photoluminescence (trPL) and differential lifetime plots.

Therefore, in this presentation, we will focus on methylammonium-lead-iodide (MAPI) thin films and the (ir)reversible introduction of traps triggered by quasi-continuous illumination. For this, we develop a method that uses long pulses of light in combination with trPL counting schemes, calling it long pulsed trPL (LP-trPL). From the method, we observe the inclusion of long lived and non-deep trapping sites due to continuous illumination. The data also suggests a highly asymmetric mechanism of trap formation, where trap annihilation is much slower than observed formation. We conclude that previously described mechanisms of iodine outgassing is compatible with the observed shallow nature of traps introduced as well as the asymmetric process of formation/annihilation.

Keywords: time resolved PL; recombination mechanisms; defect chemistry; perovskite thin films