Structural Tunability and Diversity of Two-Dimensional Lead Halide Benzenethiolate

Two-dimensional (2D) organic-inorganic hybrid materials are currently of great interest for applications in electronics and optoelectronics. Here, the synthesis and optical properties of a new type of halide-organothiolate-mixed 2D hybrid material, Pb2X(S-C6H5)(3), are reported, in which X is a halide (I, Br, or Cl). Different from conventional lead-based 2D layered materials, these compounds feature unusual five-coordinated lead centers with a stereochemically active electron lone pair on the lead atoms and four-coordinated iodine atoms. The Pb2X(S-C6H5)(3) materials feature an indirect bandgap, strongly emissive long-lived self-trap states, and an extremely large Stokes shift. Interestingly, the optical bandgap of the materials can be tuned through variation of the halides; however, the photoluminescence is less sensitive to the composition and is more likely dominated by lead-sulfur lattice interactions or the lead lone-pair electrons. Our results support that a halide-organothiolate mixed anion hybrid structure offers a unique platform for discovering new exciting 2D electronic materials.