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Insights Into the Local Heating Effects in Triple-Cation Mixed-Halide Perovskite Cells: Charge Dynamics, Coherent
Jacek J Baranowski1, Sanjay Sahare1, Mykhailo Solovan1
1Faculty of Physics and Astronomy, Adam Mickiewicz University, Poznan, 61-614, Poland.
Small (Weinheim an Der Bergstrasse, Germany)
|January 16, 2025
Summary
Investigating perovskite solar cells (PSCs) under ultrashort laser pulses reveals that increased laser energy affects carrier cooling and charge decay. Local heating also influences ion segregation dynamics within the PSCs.
Area of Science:
- Materials Science
- Photovoltaics
- Solid-State Physics
Background:
- Perovskite solar cells (PSCs) are promising photovoltaic materials.
- Understanding their behavior under intense light is crucial for device stability and performance.
- Femtosecond transient absorption (TA) spectroscopy is a key technique for probing ultrafast dynamics.
Purpose of the Study:
- To investigate the effects of ultrashort laser pulse irradiation on triple-cation mixed halide PSCs.
- To analyze local heating effects and their impact on carrier dynamics and ion segregation.
- To compare the effects of pulsed versus continuous irradiation.
Main Methods:
- Femtosecond transient absorption (TA) spectroscopy was employed to study PSCs under varying laser fluences.
- Analysis of carrier cooling times and charge population decay dynamics.
- Detection and analysis of coherent longitudinal acoustic phonons (CLAP) and anion segregation.
Main Results:
- Carrier cooling time increased from 230 fs to 1.3 ps with increasing fluence (2 µJ cm⁻² to 2 mJ cm⁻²).
- Charge population decay accelerated from nanoseconds to picoseconds.
- Coherent longitudinal acoustic phonons (CLAP) were observed, inducing lattice strain.
- Pulsed laser excitation induced partially reversible iodide/bromide anion segregation.
- Higher local heating at increased fluences slowed segregation (40 min to 110 min).
- Continuous irradiation resulted in less segregation than pulsed irradiation.
Conclusions:
- Ultrashort laser pulses significantly impact carrier dynamics and induce lattice vibrations (CLAP) in PSCs.
- Local heating, driven by laser fluence, modulates the rate of anion segregation.
- Pulsed laser irradiation causes more pronounced anion segregation than continuous irradiation, highlighting the importance of irradiation conditions for perovskite stability.
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