Vacancy-Ordered Hybrid Two-Dimensional Bi(III) Iodides with (100)-Oriented Dion-Jacobson Perovskite-Related...

Area of Science:

• Materials Science
• Solid-State Chemistry
• Optoelectronics

Background:

• Two-dimensional (2D) hybrid iodide perovskites are crucial for optoelectronics.
• Traditional Pb²⁺ and Sn²⁺ based perovskites face toxicity and stability issues.
• Bismuth (Bi³⁺) halide alternatives are sought after for lead-free applications.

Purpose of the Study:

• To synthesize and characterize novel Dion-Jacobson type, vacancy-ordered 2D Bi-I perovskites.
• To evaluate their optoelectronic properties, focusing on band gaps and photoresponse.
• To explore their potential as lead-free alternatives in optoelectronic devices.

Main Methods:

• Synthesis of vacancy-ordered 2D Bi-I perovskites: (H₂DAC)Bi_2/3□_1/3I₄ and (H₂DAP)Bi_1/2□_1/2I₃·(I₃)_1/2.
• Band gap measurements and photoresponse characterization.
• Density Functional Theory (DFT) calculations to support experimental findings.

Main Results:

• Synthesized two novel 2D Bi-I perovskites with varying vacancy orders.
• Observed narrower band gaps (2.11 eV and 1.97 eV) compared to Pb²⁺ analogues (2.36 eV).
• Demonstrated positive photoresponse, with enhanced performance in (H₂DAP)Bi_1/2□_1/2I₃·(I₃)_1/2 due to I₃^- ions.

Conclusions:

• Successful synthesis of lead-free 2D Bi-I perovskites.
• These materials exhibit tunable optoelectronic properties suitable for next-generation devices.
• The findings pave the way for further investigation into Bi(III)-I perovskites for optoelectronics and photovoltaics.