Self-powered photodetection driven by ferroelectric polarization has shown great potential in next-generation optoelectronic devices.H ybrid perovskite ferroelectrics that combine polarization and semiconducting properties have ap romising position within this portfolio.H erein, we demonstrate the realization of self-powered photodetection in an ew developed biaxial ferroelectric,( EA) 2 (MA) 2 Pb 3 Br 10 (1,E Ai s ethylammonium and MA is methylammonium), whichd isplaysh igh Curie temperature (375 K), superior spontaneous polarization (3.7 mCcm À2 ), and unique semiconducting nature. Strikingly,w ithout an external energy supply, 1 exhibits an direction-selectable photocurrent with fascinating attributes including high photocurrent density ( % 4.1 mAcm À2 ), high on/ off switching ratio (over 10 6 ), and ultrafast response time (96/ 123 ms);s uch merits are superior to those of the most active ferroelectric oxide BiFeO 3 .F urther studies reveal that strong inversion symmetry breaking in 1 provides adesirable driving force for carrier separation, accounting for such electrically tunable self-powered photoactive behaviors.T his work sheds light on exploring new multifunctional hybrid perovskites and advancing the design of intelligent photoelectric devices.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

The anomolous photovoltaic (APV) effect is an intriguing phenomenon and rarely observed in bulk materials that structurally have an inversion symmetry. Here, the discovery of such an APV effect in a centrosymmetric vanadate, BiVO4, where noticeable above‐bandgap photovoltage and a steady‐state photocurrent are observed in both ceramics and single crystals even when illuminated under visible light, is reported. Moreover, the photovoltaic voltage can be reversed by the stress modulation, and a sine‐function relationship between the photovoltage and stress directional angle is derived. Microstructure and strain‐field analysis reveal localized asymmetries that are caused by strain fluctuations in bulk centrosymmetric BiVO4. On the basis of the experimental results, a flexoelectric coupling via a strain‐induced local polarization mechanism is suggested to account for the APV effect observed. This work not only allows new applications for BiVO4 in optoelectronic devices but also deepens insights into the mechanisms underlying the APV effect.

Electrocaloric effect driven by electric fields displays great potential in realizing highly efficient solid-state refrigeration. Nevertheless, most known electrocaloric materials exhibit relatively poor cooling performance near room temperature, which hinders their further applications. The emerging family of hybrid perovskite ferroelectrics, which exhibits superior structural diversity, large heat exchange and broad property tenability, offers an ideal platform. Herein, we report an exceptionally large electrocaloric effect near room temperature in a designed hybrid perovskite ferroelectric [(CH3)2CHCH2NH3]2PbCl4, which exhibits a sharp first-order phase transition at 302 K, superior spontaneous polarization (>4.8 μC/cm2) and relatively small coercive field (<15 kV/cm). Strikingly, a large isothermal entropy change ΔS of 25.64 J/kg/K and adiabatic temperature change ΔT of 11.06 K under a small electric field ΔE of 29.7 kV/cm at room temperature are achieved, with giant electrocaloric strengths of isothermal ΔS/ΔE of 0.86 J·cm/kg/K/kV and adiabatic ΔT/ΔE of 370 mK·cm/kV, which is larger than those of traditional ferroelectrics. This work presents a general approach to the design of hybrid perovskite ferroelectrics, as well as provides a family of candidate materials with potentially prominent electrocaloric performance for room temperature solid-state refrigeration.