Inhibiting Sn²⁺ Oxidation with Dual-Functional Guanidines for Robust Tin Perovskite Solar Cells

Area of Science:

• Materials Science
• Renewable Energy
• Photovoltaics

Background:

• Tin halide perovskite solar cells (TPSCs) face challenges from Sn2+ oxidation and rapid crystallization, leading to high defect densities and poor charge transport.
• These factors limit the efficiency and long-term stability of TPSC devices.

Purpose of the Study:

• To develop a strategy for inhibiting Sn2+ oxidation and enhancing the stability of tin halide perovskite films.
• To improve the performance and durability of lead-free perovskite solar cells.

Main Methods:

• Two guanidine derivatives were introduced to coordinate with Sn2+ and form hydrogen bonds with halide ions, stabilizing the perovskite lattice.
• Cyanoguanidine (DICY) was used to passivate defects and reduce nonradiative recombination.

Main Results:

• The guanidine derivatives effectively inhibited Sn2+ oxidation and improved perovskite film stability.
• The DICY-modified device achieved a power conversion efficiency (PCE) of 11.81%.
• The DICY device maintained 96.53% of its initial efficiency after 2200 hours of storage in a nitrogen atmosphere.

Conclusions:

• Guanidine derivatives offer a promising approach for oxidation inhibition and stability enhancement in lead-free perovskites.
• The DICY additive demonstrates significant potential for advancing the performance and reliability of TPSC devices.