Dibenzo heterocyclic-terminated spiro-type hole transporting materials for perovskite solar cells

Spiro-type molecules remain benchmark hole transporting materials (HTMs) for high-performance perovskite solar cells (PSCs). Terminal unit engineering of spiro-type HTMs has drawn much attention to efficient and stable PSCs. In this work, we introduce dibenzofuran or dibenzothiophene as the terminal group into the spiro-type HTMs, named spiro-DBF and spiro-DBT, respectively, due to their superior carrier transport properties. The structure-property relationship introduced by varied terminal groups is studied in detail. It is noted that the molecule (spiro-DBF) with dibenzofuran edge groups exhibits higher hole mobility, better morphology on the perovskite layer and stronger hole extraction ability than spiro-OMeTAD. When used in PSCs, spiro-DBF exhibits a PCE of 21.43%, which is even higher than that of conventional spiro-OMeTAD. Moreover, the device with spiro-DBF also exhibits superior long-term stability. Thus, the results deliver some new insights for developing perfect HTMs and spiro-DBF could also be a potential HTM candidate for high-performance PSCs.

Automated summary

In this study, dibenzofuran and dibenzothiophene were introduced as terminal groups into spiro-type HTMs, and their structure-property relationship was investigated. It was found that the molecule with dibenzofuran terminal groups exhibited better performance in terms of hole mobility, perovskite layer morphology, and hole extraction ability. The PSCs using spiro-DBF achieved a power conversion efficiency of 21.43%, even higher than the conventional spiro-OMeTAD.