Non‐Planar and Flexible Hole‐Transporting Materials from Bis‐Xanthene and Bis‐Thioxanthene Units for Perovskite Solar Cells

• Published in: Helvetica chimica acta 2019-04, Vol.102 (4), p.n/a
• Main Authors: Urieta‐Mora, Javier, García‐Benito, Inés, Zimmermann, Iwan, Aragó, Juan, García‐Fernández, Pedro D., Grancini, Giulia, Molina‐Ontoria, Agustín, Ortí, Enrique, Martín, Nazario, Nazeeruddin, Mohammad Khaja
• Format: Article
• Language: English
• Subjects: bis-thioxanthenes; bis-xanthenes; Carbon; Conjugation; Energy conversion efficiency; Molecular structure; Organic chemistry; Perovskites; Photovoltaic cells; power conversion efficiency; Rigid structures; Solar cells; spiro-OMeTAD; Thermal properties; Thermodynamic properties; Thioxanthene; Transportation; Xanthene
• ISSN: 0018-019X; 1522-2675
• DOI: 10.1002/hlca.201900056

Two new hole‐transporting materials (HTMs), BX‐OMeTAD and BTX‐OMeTAD, based on xanthene and thioxanthene units, respectively, and bearing p‐methoxydiphenylamine peripheral groups, are presented for their use in perovskite solar cells (PSCs). The novelty of the newly designed molecules relies on the use of a single carbon‐carbon bond ‘C−C’ as a linker between the two functionalized heterocycles, which increases the flexibility of the molecule compared with the more rigid structure of the widely used HTM spiro‐OMeTAD. The new HTMs display a limited absorbance in the visible region, due to the lack of conjugation between the two molecular halves, and the chemical design used has a remarkably impact on the thermal properties when compared to spiro‐OMeTAD. BX‐OMeTAD and BTX‐OMeTAD have been tested in ([(FAPbI3)0.87(MAPbBr3)0.13]0.92[CsPbI3]0.08)‐based PSC devices exhibiting power conversion efficiencies of 14.19 and 16.55 %, respectively. The efficiencies reached, although lower than those measured for spiro‐OMeTAD (19.63 %), are good enough to consider the chemical strategy used as an interesting via to design HTMs for PSCs.