A Self-Powered UV Photodetector with Ultrahigh Responsivity based on Two-Dimensional Perovskite Ferroelectric Films with Mixed Spacer Cations.

Self-powered photodetectors (PDs) have the advantages of no external power requirement, wireless operation, and long life. Spontaneous ferroelectric polarizations can significantly increase the built-in electric field intensity, showing great potential in self-powered photodetection. Moreover, ferroelectrics possess pyroelectric and piezoelectric properties, beneficial for enhancing self-powered PDs. 2D metal halide perovskites (MHPs), which have ferroelectric properties, are suitable for fabricating high-performance self-powered PDs. However, the researches on 2D metal halide perovskites ferroelectrics focus on growing bulk crystals. Herein, we demonstrate 2D ferroelectric perovskite films with mixed spacer cations for self-powered PDs by mixing RP-type and DJ-type perovskite. The (BDA 0.7 (BA 2 ) 0.3 )(EA) 2 Pb 3 Br 10 film possesses overall the best film qualities with the best crystalline quality, lowest trap density, good phase purity, and obvious ferroelectricity. Based on the ferro-pyro-phototronic effect, the PD at 360 nm exhibits excellent photoelectric properties, with an ultrahigh peak responsivity of more than 93 A W -1 , a detectivity of 2.5 × 10 15 Jones, together with excellent reproducibility and stability. The maximum responsivities can be modulated by the piezo-phototronic effect with an effective enhancement ratio of 480%. Our work will open up a new route of designing MHP ferroelectric films for high-performance PDs and offers the opportunity to utilize it for various optoelectronics applications. This article is protected by copyright. All rights reserved.