Engineering Lead-Free Hybrid Halide Perovskite Quantum Wells

Halide perovskites are a relatively recent class of semiconducting materials that have caught the attention of many owing to their excellent optical and electronic properties. While lead-based perovskites still attract the most attention, concerns about their toxicity have made it vital to examine alternative materials systems (e.g., tin-based perovskites). Lower-dimensional tin perovskites have a higher degree of tunability and better stability compared to their 3D counterpart. However, most organic ligands incorporated in 2D perovskites are electrically insulating and hinder charge transport in the materials. Here, we design and synthesize novel semiconducting ligands for 2D tin perovskites to demonstrate precise energy level alignment between the organic and inorganic layers. Functionalizing the ligand with different donor and acceptor groups help finetune the bandgap and improve charge transfer in the perovskite. Based on the positioning of the levels, the ligands aid in either funneling the charge carriers to one layer or efficiently separating them. As a result, devices made with tin perovskites containing the novel ligands can be made comparable to the impressive performance of lead-based devices making them a viable alternative.