Spiro-OMeTAD single crystals: Remarkably enhanced charge-carrier transport via mesoscale ordering

Dong Shi, X. Qin, Yuan Li, Yao He, Cheng Zhong, Jun Pan, H. Dong, Wei Xu, T. Li, W. Hu, Jean-Luc Bredas, Osman Bakr

Research output: Contribution to journalArticlepeer-review

73 Scopus citations

Abstract

We report the crystal structure and hole-transport mechanism in spiro-OMeTAD [2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenyl-amine)9,9′-spirobifluorene], the dominant hole-transporting material in perovskite and solid-state dye-sensitized solar cells. Despite spiro-OMeTAD’s paramount role in such devices, its crystal structure was unknown because of highly disordered solution-processed films; the hole-transport pathways remained ill-defined and the charge carrier mobilities were low, posing a major bottleneck for advancing cell efficiencies. We devised an antisolvent crystallization strategy to grow single crystals of spiro-OMeTAD, which allowed us to experimentally elucidate its molecular packing and transport properties. Electronic structure calculations enabled us to map spiro-OMeTAD’s intermolecular charge-hopping pathways. Promisingly, single-crystal mobilities were found to exceed their thin-film counterparts by three orders of magnitude. Our findings underscore mesoscale ordering as a key strategy to achieving breakthroughs in hole-transport material engineering of solar cells.
Original languageEnglish (US)
Pages (from-to)e1501491
JournalScience Advances
Volume2
Issue number4
DOIs
StatePublished - Apr 15 2016

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