A Domino Protocol toward High‐performance Unsymmetrical Dibenzo[d,d′]thieno[2,3‐b;4,5‐b′]dithiophenes Semiconductors

Unsymmetric organic semiconductors have many advantages such as good solubility, rich intermolecular interactions for potential various optoelectronic applications. However, their synthesis is more challenging due to intricate structures thus normally suffering tedious synthesis. Herein, we report a trisulfur radical anion (S3⋅−) triggered domino thienannulation strategy for the synthesis of dibenzo[d,d′]thieno[2,3‐b;4,5‐b′]dithiophenes (DBTDTs) using readily available 1‐halo‐2‐ethynylbenzenes as starting materials. This domino protocol features no metal catalyst and the formation of six C−S and one C−C bonds in a one‐pot reaction. Mechanistic study revealed a unique domino radical anion pathway. Single crystal structure analysis of unsymmetric DBTDT shows that its unique unsymmetric structure endows rich and multiple weak S⋅⋅⋅S interactions between molecules, which enables the large intermolecular transfer integrals of 86 meV and efficient charge transport performance with a carrier mobility of 1.52 cm2 V−1 s−1. This study provides a facile and highly efficient synthetic strategy for more high‐performance unsymmetric organic semiconductors. A trisulfur radical anion (S3.−) triggered domino thienannulation strategy for the synthesis of dibenzo[d,d′]thieno[2,3‐b;4,5‐b′]dithiophenes (DBTDTs) has been developed. This domino protocol is featured by no metal catalyst and the formation of six C−S and one C−C bonds in one‐pot reaction. A plausible mechanism has been proposed by control experiments, intermediate trapping experiments, etc. The unique unsymmetric structure of DBTDT endows it with herringbone packing structure and weak S⋅⋅⋅S interactions between molecules as well as high transfer integrals, which enables a high carrier mobility of 1.52 cm2 V−1 s−1 in organic field‐effect transistors.