Modulation of Planarity on Carbazole Derivatives-Based Hole Transport Materials for Perovskite Solar Cells: A Theoretical and Experimental Research

Three well-honed carbazole derivatives-based hole transport materials (HTMs) with benzene, naphthalene, and anthracene as the core were designed on the basis of the reported triphenylamine-based B101. In order to systematically explore the effect of planarity on the performance of HTMs, the properties of the materials were evaluated theoretically. The calculated results indicate that the carbazole derivatives-based HTMs (HY1–HY3) exhibit better properties than the parental B101, such as lower HOMO levels and higher hole mobility. A candidate material, HY1, with remarkable hole mobility was synthesized and applied in perovskite solar cells (PSCs) to verify the theoretical results. According to the experimental results, the power conversion efficiency (PCE) of the dopant-free HY1-based PSC device is superior to a dopant-free B101-based device, due to its low HOMO levels and high hole mobility. Especially, the addition of HY1 in Spiro-OMeTAD as mixed HTMs (Spiro-OMeTAD + 3 mg HY1) in PSC applications can yield a maximum PCE of 17.81%, significantly higher than that of the control device using Spiro-OMeTAD as HTM (16.64%). Therefore, modulating the planarity of the molecules is an effective strategy to obtain potential HTMs with deep HOMO levels and high hole mobility for improving the performance of PSC devices. Graphical Abstract