Enhancing the hole-conductivity of spiro-OMeTAD without oxygen or lithium salts by using spiro(TFSI)₂ in perovskite and dye-sensitized solar cells

William H Nguyen; Colin D Bailie; Eva L Unger; Michael D McGehee

doi:10.1021/ja504539w

Enhancing the hole-conductivity of spiro-OMeTAD without oxygen or lithium salts by using spiro(TFSI)₂ in perovskite and dye-sensitized solar cells

J Am Chem Soc. 2014 Aug 6;136(31):10996-1001. doi: 10.1021/ja504539w. Epub 2014 Jul 29.

Authors

William H Nguyen¹, Colin D Bailie, Eva L Unger, Michael D McGehee

Affiliation

¹ Department of Chemistry and †Department of Materials Science and Engineering, Stanford University , Stanford, California 94305, United States.

PMID: 25051503
DOI: 10.1021/ja504539w

Abstract

2,2',7,7'-Tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD), the prevalent organic hole transport material used in solid-state dye-sensitized solar cells and perovskite-absorber solar cells, relies on an uncontrolled oxidative process to reach appreciable conductivity. This work presents the use of a dicationic salt of spiro-OMeTAD, named spiro(TFSI)2, as a facile means of controllably increasing the conductivity of spiro-OMeTAD up to 10(-3) S cm(-1) without relying on oxidation in air. Spiro(TFSI)2 enables the first demonstration of solid-state dye-sensitized solar cells fabricated and operated with the complete exclusion of oxygen after deposition of the sensitizer with higher and more reproducible device performance. Perovskite-absorber solar cells fabricated with spiro(TFSI)2 show improved operating stability in an inert atmosphere. Gaining control of the conductivity of the HTM in both dye-sensitized and perovskite-absorber solar cells in an inert atmosphere using spiro(TFSI)2 is an important step toward the commercialization of these technologies.