Tunable 2D Hybrid Perovskites with Pd(II) Adsorption and Semiconducting Properties

Layered hybrid perovskites, due to their broad application potential in optical, electrical, and luminescence fields, are attracting increasing attention. Herein, we report two novel two-dimensional hybrid organic-inorganic perovskites [C₅H₁₀N₂S]PbBr₄ (1) and [C₅H₁₀N₂S]PbI₄ (2) ([C₅H₁₀N₂S]²⁺ is 3-ethylaminothiazolium), which possess phase transition and semiconductor properties. Intriguingly, 1 has semiconductor properties with an optical band gap of 2.70 eV and a photocurrent to dark current ratio of 50 for the photoresponse. By varying the halogen, the band gap of 2 is significantly reduced to 2.06 eV and the photocurrent to dark current ratio of the photoresponse reaches 10⁴. Moreover, compounds 1 and 2 are able to adsorb Pd(II) resulting from the presence of -SH groups in the cation. The adsorption of Pd(II) can turn a semiconductor into an insulator, weaken the fluorescence intensity, and cause the phase transition behavior to disappear. This work has remarkable implications for the continuous development of hybrid perovskites with phase transitions, metal adsorption, and semiconductor properties.