Researchers from Konkuk University, Tokyo University of Agriculture and Technology and Nanoenics have reported an improved crystallization of hybrid perovskite films achieved through the addition of a potent antioxidant derived from garlic, known as allicin. Oxidation of hybrid perovskite composed of organic–inorganic materials can cause significant problems in performance and stability of perovskite solar cells (PSCs), because the hybrid perovskite oxidation induces considerable decrease in crystallinity and quality of hybrid perovskites.
Defect sites within the hybrid perovskite film, which arise during annealing and ageing processes, were found to be effectively managed by the antioxidant properties of allicin, particularly at elevated temperatures. Acting as an in situ encapsulator for the hybrid perovskite, the antioxidant efficiently regulated defect sites by supplying protons and neutralizing free radicals.
The team acquired the antioxidants from garlic through solvent extraction, the most common method for obtaining natural antioxidants. Garlic extracts possess both allicin and polyphenols, whose proportions affect the antioxidative capacity of garlic extracts. The proportions of allicin and polyphenols are determined by the extraction solvent. The garlic-extracted antioxidants were dissolved in hybrid perovskite precursor solution and applied to PSCs.
Consequently, the addition of the antioxidants to the hybrid perovskite film facilitated charge-trap passivation and charge extraction, resulting in an increase in PCE from 22.89 to 24.50%.
Moreover, the encapsulated PSC by the antioxidants retained approximately 92% of its initial PCE even after exposure to ambient conditions for over 190 days.
This study provides effective and eco-friendly guidelines for suppressing the oxidation of hybrid perovskite, achieving both high efficiency and stability in PSCs.
