Ethanol-assisted synthesis of two-dimensional tin(ii) halide perovskite single crystals for amplified spontaneous emission

Two-dimensional (2D) Ruddlesden-Popper perovskites (RPPs) are emerging as star materials for their superior optoelectronic properties. In particular, lead-free tin(ii)-based 2D RPPs have recently gained more attention. However, until now, 2D tin(ii)-based perovskite lasing has not been achieved. High-quality single crystals (SCs) with a low trap density are a good gain medium candidate for lasing. Unfortunately, research on the controllable synthesis of tin(ii)-based SCs is still very limited. In this work, we developed a novel synthesis strategy in which ethanol was introduced to control the solubility of the perovskite precursors. We prepared high-quality RPP (TEA)(2)(MA)(n-1)SnnI3n+1 (n = 1 or n = 2, TEA = 2-thiopheneethylamine, MA = methylamine) SCs, and investigated their structural and optical properties. The exciton binding energy of tin(ii)-based 2D perovskites was fitted to 184.1 meV and 46.13 meV for (TEA)(2)SnI4 (n = 1) and (TEA)(2)(MA)Sn2I7 (n = 2) SCs, respectively, which is much higher than for polycrystalline thin films. We further investigated the optical gain behavior of the tin(ii)-based 2D perovskites. The amplified spontaneous emission (ASE) of exfoliated SCs was demonstrated at 20 K with a threshold of 29.1 mu J cm(-2) for (TEA)(2)SnI4 (n = 1) and 630.1 mu J cm(-2) for (TEA)(2)(MA)Sn2I7 (n = 2).

Automated summary

Lead-free tin(ii)-based 2D Ruddlesden-Popper perovskites have recently gained attention for their superior optoelectronic properties. However, achieving tin(ii)-based 2D perovskite lasing has been a challenge. In this study, a novel synthesis strategy using ethanol was developed to control the solubility of the perovskite precursors, leading to the successful preparation of high-quality single crystals. The structural and optical properties of the tin(ii)-based 2D perovskites were investigated, and their optical gain behavior was demonstrated.