A centimeter-scaled lead-free two-dimensional perovskite FA3Bi2Br9 single crystal for X-ray detection

Abstract

As a newly emerged lead-free two-dimensional (2D) organic–inorganic hybrid perovskite, FA₃Bi₂Br₉ has shown promising potential for optoelectronic applications due to its excellent optical and electronic properties. However, the growth of large and high-quality single crystals (SCs) of FA₃Bi₂Br₉ has been challenging. Furthermore, the feasibility of its application for X-ray detection remains unexplored. Here we report the growth of centimeter-scaled high-quality FA₃Bi₂Br₉ perovskite SCs via a controlled slow cooling method. Structural, optical, and electrical properties and the environmental stability of FA₃Bi₂Br₉ SCs have been investigated. The 2D FA₃Bi₂Br₉ SCs exhibit a low trap density of 5.66 × 10⁹ cm⁻³ and a high carrier mobility–lifetime product (μτ) of 4.15 × 10⁻⁴ cm⁻² V⁻¹ as well as a high resistivity of 1.76 × 10¹⁰ Ω cm, endowing the FA₃Bi₂Br₉ SC X-ray detector with a high sensitivity of 623 μC Gy⁻¹ cm⁻². The results demonstrate that the lead-free 2D perovskite FA₃Bi₂Br₉ SCs offer a promising choice for eco-friendly and sensitive radiation detection.