Toward Water-Resistant, Tunable Perovskite Absorbers Using Peptide Hydrogel Additives

Area of Science:

• Materials Science
• Renewable Energy
• Nanotechnology

Background:

• Organometal halide perovskites (OHPs) show promise for solar cells but suffer from poor stability and optical property limitations.
• Hydrogels, particularly petrochemical-derived polymers, are explored as additives to improve OHP performance and durability.
• Defect sites in perovskites act as charge recombination centers, reducing efficiency and stability.

Purpose of the Study:

• To investigate the role of a peptide hydrogel in passivating defect sites and enhancing the stability of methylammonium lead iodide (MAPI).
• To evaluate the impact of peptide hydrogel incorporation on the optical properties, crystallite size, and surface stoichiometry of MAPI.
• To assess the performance and stability of MAPI-based devices with varying peptide hydrogel concentrations under different environmental conditions.

Main Methods:

• Fabrication of MAPI thin films with varying peptide hydrogel concentrations using a conventional one-step approach.
• In situ X-ray photoelectron spectroscopy (XPS) under controlled vacuum and near-ambient water vapor pressures to analyze surface chemistry and degradation.
• Optical measurements to determine defect density and bandgap, alongside power conversion efficiency (PCE) measurements of fabricated devices.

Main Results:

• Peptide hydrogel incorporation reduced defect sites, leading to improved optical properties and a larger optical bandgap consistent with quantum size effects.
• XPS confirmed encapsulation of MAPI crystallites and demonstrated reduced thermal degradation in vacuum and improved stability against methylammonium loss under water vapor.
• Devices with 3 wt % peptide loading achieved a maximum PCE of 16.6% and retained 81% of their initial efficiency after 480 hours, significantly outperforming control devices.

Conclusions:

• Peptide hydrogels are effective additives for passivating defects and enhancing the stability and performance of MAPI perovskites.
• The study demonstrates a viable strategy for improving the operational lifetime of perovskite solar cells through bio-derived material integration.
• Optimized peptide loading offers a pathway to high-efficiency and durable perovskite solar cell technologies.