A Spirobixanthene‐Based Dendrimeric Hole‐Transporting Material for Perovskite Solar Cells

A dendrimer based on a spirobixanthene core, termed DH1, is designed and synthesized as a hole‐transporting material (HTM) for perovskite solar cells (PSCs). DH1 showing a hyperbranched structure with methoxydiphenylamine carbazole dendrons stretching outward along the para‐phenylene spacer acquires a large molecular size of up to 1.9 nm, which favors good thermal stability and amorphous property. The thus obtained DH1‐based pinhole‐free film as a hole‐transport layer results in a power conversion efficiency of 17.13% and reduced hysteresis behavior of MAPbI₃‐based planar PSCs. This work provides the first example of the use of dendrimer‐type HTM for PSC application, demonstrating a promising approach to design HTMs in a quasiglobular dendrimer with a large molecular size.