Benzotrithiophene‐Based Covalent Organic Frameworks: Synthesis and Application to Perovskite Solar Cells

Two benzotrithiophene (BTT)‐based 2D covalent organic frameworks (2D COFs) are synthesized and characterized. The BTT and triphenylamine units (either tris(4‐aminophenyl)amine or N 4, N 4‐bis(4′‐amino‐[1,1′‐biphenyl]‐4‐yl)‐[1,1′‐biphenyl]‐4,4′‐diamine) are alternately connected for the two BTT‐based COFs, namely TABT–COF and BABT–COF, respectively. The obtained BTT‐based COFs exhibit high crystallinity, high surface area, and excellent thermal stability. In addition, these two COFs are further utilized as efficient additives by doping into the perovskite layer of perovskite solar cells (PSCs). The incorporation of BTT‐based COFs can be exploited as an efficient nucleation template, enabling the regulation of perovskite crystallinity. The power conversion efficiencies of the champion PSCs with TABT–COF and BABT–COF achieve 18.10% and 18.56%, respectively, outperforming that (16.58%) of the control device.