Abstract
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.
Highlights
Electrocaloric effect driven by electric fields displays great potential in realizing highly efficient solid-state refrigeration
In contrast to traditional inorganic perovskite ferroelectrics[9,15,35,36,37], which traditionally display purely displacive phase transitions accompanied with small entropy changes, the high degree of ordering and disordering of dipoles in hybrid perovskite structure of 1 will result in multiple ferroic orders associated with large isothermal entropy changes
In comparison between 1 and other known promising EC materials in terms of cooling performance (Table 1 and Fig. 4e), it can be noticed that the operating temperature of 1 is near room temperature (302 K), which is crucial for practical cooling applications
Summary
Electrocaloric effect driven by electric fields displays great potential in realizing highly efficient solid-state refrigeration. 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. Most of them suffer from poor cooling performance, large driving electric fields, and operational temperature far away from room temperature, which becomes the potential bottleneck to their practical applications in cooling devices In this context, it is highly imperative to develop ferroelectric materials which are capable of generating a giant EC effect near room temperature for high-performance solid-state refrigeration. Taking into consideration of the superior structural diversity, large heat exchange, and broad property tenability, it is expected that hybrid perovskites could offer great opportunities to achieve highperformance room temperature EC refrigeration
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