Enhanced exciton–phonon coupling in pseudohalide 2D perovskite for X-ray to visible light detection

Abstract

Two-dimensional Cs₂Pb(SCN)₂I₂ perovskite has an ultra-small interlayer spacing, inducing a series of interesting semiconductor properties, such as efficient interlayer carrier transport as well as lower exciton binding energy compared to perovskites with long alkylammonium cations. The prepared Cs₂Pb(SCN)₂I₂ photodetector achieves a high on/off ratio of 2.1 × 10⁴ with a specific detectivity of 6.2 × 10¹¹ jones to 450 nm visible light, and a high sensitivity of 2747 μC Gy_air⁻¹ cm⁻² to X-rays.