Spin Texture Sensitive Photodetection by Dion-Jacobson Tin Halide Perovskites

Area of Science:

• Materials Science
• Condensed Matter Physics
• Optoelectronics

Background:

• Organic spacer molecules critically influence the optoelectronic properties of 2D perovskites.
• Spacer layer thickness impacts the structural characteristics of the inorganic layer, thereby governing optical transition types.

Purpose of the Study:

• To investigate how spacer layer thickness affects optical transitions (direct/indirect) and optoelectronic performance in 2D perovskites.
• To explore the role of spin-orbit interactions and electron spin texture in high-performance lead-free perovskite photodetectors.

Main Methods:

• Fabrication and characterization of mixed halide Sn2+ Dion-Jacobson (DJ) perovskites with varying diammonium spacer lengths (4-C, 6-C, 8-C).
• Analysis of optical transition properties, including direct and indirect components, influenced by structural and spin-orbit effects.
• Evaluation of photodetector performance metrics such as responsivity and detectivity under varying bias conditions.

Main Results:

• Spacer thickness dictates the direct or indirect nature of optical transitions by controlling inorganic layer structure.
• Shorter spacers (e.g., 4-C) enhance the direct optical transition component, leading to superior optoelectronic performance.
• The 4-C DJ perovskite with equimolar Br/I exhibits exceptional responsivity (78.1 A W-1) and self-powered photodetection capabilities (0.085 A W-1, 9.9 × 1010 jones).

Conclusions:

• Spacer layer engineering is a key strategy for tuning optoelectronic properties in 2D perovskites.
• The electron spin texture plays a significant role in the high performance of lead-free DJ perovskite photodetectors.
• These findings open possibilities for developing spin-based semiconductor devices without external magnetic fields or ferromagnetic materials.