Extended π-conjugated cores on arylamine derivative-based hole-transporting materials for perovskite solar cells: theoretical design and experimental research

Abstract

Hole-transporting materials (HTMs) have a vital influence on the improvement of performance for perovskite solar cells (PSCs). Starting from arylamine-based HTM (e.g., Spiro-OMeTAD), we design three molecules (CQ4–CQ6) with different conjugated π-bridge cores with a fused aromatic ring instead of the single carbon atom. To achieve a goal that provides an effective strategy for HTMs design, the frontier molecular orbitals, optical absorptions, and hole transport for these HTMs in this work were investigated using DFT and TD-DFT combined with Marcus theory. The simulated results indicated that CQ4 with better performance, such as good charge separation, smaller recombination energy, and the highest hole mobility, may be an alternative HTM for PSC applications. Therefore, the promising HTM of CQ4 was synthesized and further applied to PSC devices. The results show that the power conversion efficiency (PCE) of the Spiro-OMeTAD-based PSC device is 17.12%, while the CQ4-based PSC shows a better PCE of 17.48%, due to its high hole mobility and uniform smooth film morphology, which ultimately promoted a higher fill factor. In addition, the experimental data can reproduce the theoretical results very well, indicating that the provided model of molecular design is a feasible way to obtain the alternative HTMs.