Pyrrolidino[2,1-a]phthalazino[60]fullerenes: A New Family of Fullerene Derivatives for Photovoltaic Applications

A reaction of phthalaldehyde with tosylhydrazide and alcohols, used as solvents, is serendipitously discovered, resulting in the formation of the corresponding phthalazinium salts. The obtained salts represent convenient precursors for the generation of azomethine ylides and readily functionalize the fullerene C-60 upon treatment with a base to produce a new family of fullerene derivatives bearing pyrrolidino[2,1-a]phthalazine moiety on the fullerene cage. The revealed reaction provides a convenient synthetic route for the preparation of a broad variety of fullerene derivatives incorporating the substituents stemming from readily accessible alcohols. The obtained fullerene derivatives are investigated as electron-transport materials in p-i-n perovskite solar cells and delivered encouraging power conversion efficiencies of >14%. The ease of the preparation and tunability of optoelectronic properties of pyrrolidino[2,1-a]phthalazino[60]fullerenes make them highly promising materials for organic electronics and photovoltaics.

Automated summary

The reaction of phthalaldehyde with tosylhydrazide and alcohols unexpectedly leads to the formation of phthalazinium salts, which can be used as precursors for generating azomethine ylides and functionalizing the fullerene C-60. These fullerene derivatives, incorporating substituents from readily accessible alcohols, show encouraging power conversion efficiencies in perovskite solar cells and possess tunable optoelectronic properties for potential application in organic electronics and photovoltaics.