Crystal Growth Modulation of Tin-Lead Halide Perovskites via Chaotropic Agent

Area of Science:

• Materials Science
• Photovoltaics
• Solid-State Chemistry

Background:

• Mixed tin-lead (Sn-Pb) halide perovskites offer tunable bandgaps for efficient all-perovskite tandem solar cells.
• Commercial viability and stability of Sn-Pb perovskite solar cells (PSCs) are hindered by challenges in film quality and performance.
• Additives are crucial for optimizing Sn-Pb perovskite crystallization, but their photophysical mechanisms are not fully understood.

Purpose of the Study:

• To elucidate the mechanistic role of guanidinium thiocyanate, a chaotropic agent, in the crystallization of Sn-Pb perovskites.
• To investigate how additives influence crystal growth, film homogeneity, and optoelectronic properties of Sn-Pb PSCs.
• To explore the impact of cooldown dynamics on perovskite film photophysics.

Main Methods:

• Hyperspectral imaging combined with real-time in situ photoluminescence spectroscopy.
• Analysis of Sn-Pb perovskite crystallization processes.
• Characterization of film properties and device performance.

Main Results:

• Guanidinium thiocyanate modulates crystal growth rate, leading to more homogeneous Sn-Pb perovskite films.
• Reduced nonradiative recombination and enhanced photoluminescence quantum yield (7.28%).
• Extended charge carrier lifetime (>11 μs) and high device efficiency (22.34%) with a fill factor over 80%.

Conclusions:

• The chaotropic agent guanidinium thiocyanate enhances Sn-Pb perovskite crystallization and film quality.
• Understanding cooldown dynamics is crucial for optimizing perovskite optoelectronic properties.
• This study advances the design of high-quality Sn-Pb perovskites for efficient and stable solar cells.