Epitaxial Electrodeposition of 2D-Layered BiI₃ and Conversion to Highly Ordered Bi-Based Organic-Inorganic Halide-Based Perovskites


Highly-ordered, epitaxial semiconductor thin films have low defect densities and excellent photo-physical properties that are desired for optoelectronic devices. Single crystalline perovskite materials are known to provide lower trap densities, a larger diffusion length, and higher photo-conversion efficiencies in perovskite solar cells. However, the preparation of cost-effective, highly ordered semiconductor films with a uniform surface morphology, low electron-hole recombination, and low trap densities remains a bottleneck to achieve higher device efficiencies in large-area electronics. Electrodeposition is a deposition route that is highly scalable and provides a variety of deposition parameters such as potential, pH, temperature, and additives that can be tuned to produce highly ordered epitaxial films with controlled morphologies. Bismuth triiodide, BiI3, is a 2D-metal halide semiconductor that crystallizes in a R (H) space group symmetry with lattice parameters of a = b = 0.7516 nm, c = 2.0718 nm. BiI3 possesses a structure with repeating units of the I-Bi-I plane, in which a monolayer of Bi atoms is sandwiched between two layers of iodide with strong Bi-I ionic bonds. We deposited epitaxial BiI3 films on Au(111) substrate electrochemically by reducing I2 in the presence of Bi3+. The epitaxial films of the solar light-absorbing perovskite (CH3NH3)3Bi2I9 are produced in a solution from BiI3 by topotactic transformation.

Meeting Name

240th ECS Meeting (2021: Oct. 10-14, Virtual)



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Article - Journal

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Publication Date

21 Oct 2021