Hybrid Perovskites Depth Profiling with Variable-Size Argon Clusters and Monatomic Ions Beams

Area of Science:

• Materials Science
• Surface Science
• Analytical Chemistry

Background:

• Ion beam depth profiling is essential for analyzing multilayered devices like solar cells.
• Hybrid perovskite layers and perovskite solar cells present unique challenges due to organic/inorganic interfaces.
• Optimizing sputtering conditions is critical to avoid material modification during analysis.

Purpose of the Study:

• To optimize ion beam sputtering conditions for depth profiling of perovskite solar cells.
• To compare the effectiveness of monatomic and cluster ion beams on hybrid perovskite materials.
• To identify sputtering parameters that minimize artifacts and ensure accurate interface characterization.

Main Methods:

• Depth profiling of model perovskite samples and full solar cells using low-energy monatomic (Ar⁺, Cs⁺) and variable-size argon cluster (Ar_n⁺) ion beams.
• Systematic comparison of sputtering rates and surface modifications under various beam conditions.
• Characterization using X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and in-situ scanning probe microscopy (SPM).

Main Results:

• 500 eV Cs⁺ monatomic beams yielded stable ToF-SIMS profiles, material-independent sputtering rates, and sharp interfaces.
• Large argon clusters (n > 500) at low energies (< 10 keV) caused preferential sputtering and metal cluster accumulation.
• Optimized argon clusters (300 < n < 500) at ~20 eV/atom provided low organic fragmentation, suitable erosion rates, and constant molecular profiles without damage accumulation.

Conclusions:

• Low-energy Cs⁺ monatomic beams are effective for perovskite depth profiling.
• Optimized argon cluster ion beams (300-500 atoms, ~20 eV/atom) minimize artifacts and enable accurate analysis of perovskite solar cells.
• Careful selection of ion beam conditions is paramount for reliable depth profiling of complex organic-inorganic hybrid materials.