Boosting the performance of D-A-D type hole-transporting materials for perovskite solar cellsviatuning the acceptor group

In this work, two novel electron-deficient groups phenanthrothiadiazole (PT) and triphenylenobisthiadiazole (TBT) are utilized to construct donor-acceptor-donor (D-A-D) type hole-transporting materials (HTMs). The electronic, optical and charge transport properties are evaluated by performing quantum chemical calculations. Our results show that, in comparison with that of the benzothiadiazole (BT,SM-1) unit, the newly designedSM-2andSM-3display more deep highest occupied molecular orbital (HOMO) energy levels. Meanwhile, the blue-shifted light absorption spectra are also obtained, which will be helpful in enhancing the absorption of the perovskite layer. Unfortunately, the hole mobilities ofSM-2andSM-3are slightly lower than that ofSM-1due to the weak intermolecular electronic coupling. In addition, we also find that better solubility and stable dimeric configuration are obtained for the new HTMs. Overall, this work provides some useful clues for designing new acceptor structures in D-A-D-type HTMs, and a potential HTMSM-3is proposed.