Emissive Nature and Molecular Behavior of Zero-Dimensional Organic-Inorganic Metal Halides Bmpip2MX4.

Zero-dimensional (0D) organic-inorganic metal halides, with their high stability and broadband emission features, have aroused great interest in optoelectronic applications. Metal halides of the type Bmpip2MX4 (M = Pb, Sn, or Ge; X = I or Br) have 0D disphenoidal coordinated structures that offer an excellent opportunity to investigate their emissive nature and molecular behavior. Herein, the photophysical properties and carrier transport behavior of 0D Bmpip2MX4 metal halides are studied by using density functional theory. Our results indicate that Bmpip2MX4 metal halides present broadband emission widths and significant Stokes shifts. In particular, Bmpip2SnBr4 possesses the largest Stokes shift (1.981 eV) and the shortest exciton self-trapping time, demonstrating the best photoluminescence emission ability. Bmpip2GeI4 exhibits the lowest electron-hole creation energy and the best photoresponse capacity. Moreover, Bmpip2PbI4 demonstrates superior transport capabilities with high carrier mobilities of 4.56 × 10-3 and 2.51 × 10-7 cm2 V-1 s-1 for hole and electron carriers, respectively, which makes it comparable even with typical hole transport materials (e.g., RR P3HT, ∼10-4 cm2 V-1 s-1). These findings highlight exciting opportunities for the future development and application of such kinds of 0D metal halides in optoelectronics.