Centimeter-sized novel two-dimensional organic lead–tin mixed iodide single crystals for efficient photodetector applications

Abstract

Two-dimensional (2D) organic–inorganic halide perovskites (OIHPs) are referred to as a class of perovskites with higher stability than the typical 3D counterparts. However, the so-far reported 2D OIHPs with satisfactory performances have basically concentrated on pure Pb-based materials, and a critical challenge is to explore less hazardous perovskites that still have comparable performances and high stability. In this study, through rational design, we grew a series of 2D Pb–Sn-alloyed samples (C₈H₉F₃N)₂Pb_1−xSn_xI₄ (x = 0, 0.5, 1) by introducing hydrophobic conjugated molecules 4-(trifluoromethyl) benzylamine as organic components. Systematic structural, photophysical, and electrical studies as well as stability measurements were performed and the photodetectors were constructed with a symmetrical lateral device architecture. All the (C₈H₉F₃N)₂Pb_1−xSn_xI₄-based devices displayed obvious photoresponse behaviors. It was interesting to observe that the (C₈H₉F₃N)₂Pb_0.5Sn_0.5I₄ single crystal demonstrated the highest stability and the best performances, with the highest responsivity (∼668.1 mA W⁻¹) and detectivity (8.6 × 10¹⁰ cm Hz^l/2 W⁻¹) under the illumination of a 405 nm laser. This study provides a metal-alloying strategy for constructing 2D perovskites with reduced Pb contents and enhanced properties.