Beyond efficiency: Phenothiazine, a new commercially viable substituent for hole transport materials for perovskite solar cells

Michal Robert Maciejczyk, Ruihao Chen, Alasdair Angus Macintyre Brown, Nanfeng Zheng, Neil Robertson

Research output: Contribution to journalArticlepeer-review

Abstract

Two triphenylbenzene (TPB) derivatives, 1,3,5-Tris(2’-((N,N-di(4-methoxyphenyl)amino)phenyl)benzene (TPB(2-MeOTAD)) and 1,3,5-Tris(2’-(N-phenothiazylo)phenyl)benzene (TPB(2-TPTZ)) have been synthesized via two cost-efficient two step process, and fully characterized by 1H/13C NMR spectroscopy and mass spectrometry. For the first time in perovskite solar cells, phenothiazine has been introduced, as a low cost substituent to replace commonly used dimethoxydiphenylamine-which consitute of almost 90% of the final cost of hole transporting materials (HTMs). The use of a more flexible central core than state of the art spirobifluorene (SBF) lowers the highest occupied molecular orbital (HOMO) energy level, increases solubility and decreases the glass transition temperature. The derivatives were employed as hole-transport materials, and their performances were compared via the fabrication of mesoporous ZnO-Mg-EA(NH3+)/CH3NH3PbI3/HTM/Au solar cells. The best cells obtained have a optimized PCE of 12.14% and 4.32% for cells based on 4,4’-dimethoxydiphenylamine and phenothiazine substituent, respectively. Due to the extremely low cost of TPB(2-TPTZ) equal to 3.43 $/g, in solar cells it delivers the lowest cost per peak Watt of 0.014 $/Wp, which is 15 times lower than spiro-MeOTAD. This shows that the approach is commercially viable with potential to deliver HTM with cost contribution to final module as little as 1%.
Original languageEnglish
JournalJournal of Materials Chemistry C Materials for optical and electronic devices
Early online date24 Jun 2019
DOIs
Publication statusE-pub ahead of print - 24 Jun 2019

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