Comparative 1‐Propanol Vapor Sensing Performance of 3D MAPbBr ₃ and 2D (PEA) ₂ PbBr ₄

ABSTRACT Metal halide perovskites have emerged as a highly promising class of materials, garnering immense scientific and technological interest in recent years. Their exceptional properties make them particularly attractive for a wide range of optoelectronic applications, most notably in high‐efficiency solar cells and advanced photodetectors. Beyond these uses, hybrid perovskite materials have also demonstrated potential as sensitive platforms for detecting volatile organic compounds, further expanding their technological relevance. It has been demonstrated that the adsorption of these organic molecules can passivate surface defects, which improves the conductance of the perovskite layer. Here, we show that methylammonium lead bromide (MAPbBr 3 ) and 2‐phenylethylammonium lead bromide ((PEA) 2 PbBr 4 ) are highly effective in sensing 1‐propanol, which has been identified as biomarker for lung cancer. Both systems exhibit a response time of 1 s, and a recovery time of 1.7 and 14 s for MAPbBr 3 and (PEA) 2 PbBr 4 , respectively. Going from a 3D to a 2D structure allows us to tailor electronic properties and trap density states, thereby greatly enhancing gas sensitivity. Both systems show a remarkable maximum response of 10 6 and 10 7 at 6000 and 7000 ppm, respectively, and a low detection limit of 90 ppm.