Ferroelectric perovskite-type films with robust in-plane polarization toward efficient room-temperature...

Ferroelectric materials have become key components for versatile device applications, and their thin films are highly desirable for integrating the miniaturized devices. Despite substantial endeavors, it is still challenging to achieve effective chemiresistive sensing in the ferroelectric films. Here, for the first time, we have exploited ferroelectric thin films of 2D hybrid perovskite BA₂EA₂Pb₃I₁₀ (1), to fabricate the high-performance chemiresistor gas sensors. The spin-coated films of 1 exhibit high orientation and good crystallinity, thus preserving robust in-plane spontaneous polarization (P _s ∼2.0 μC/cm²) and low electric coercivity. Notably, such ferroelectric film-based sensors after electric poling enable the dramatic room-temperature sensing responses to NO₂ gas, including high sensitivity (0.05 ppm^-1), extremely low detection limit (1 ppm) and fast responding rate (∼6 s). Besides, the chemiresistive responses are remarkably enhanced by threefold (up to 320%) through electric poling. It is proposed that this behavior closely involves with strong in-plane ferroelectric polarization of 1 that generates a built-in electric field inhibiting the recombination of charge carriers. As far as we know, this ferroelectric-based film chemiresisor is one of the best room-temperature sensors for NO₂ gas among all the existing candidate materials. These findings highlight great potential of ferroelectrics toward effective chemiresistive performances, and also establish a bright direction to explore their future device applications.