Enhanced Electrocaloric Response of Vinylidene Fluoride–Based Polymers via One‐Step Molecular Engineering

Abstract Electrocaloric refrigeration is one of the most promising environmentally‐friendly technologies to replace current cooling platforms—if a notable electrocaloric effect (ECE) is realized around room temperature where the highest need is. Here, a straight‐forward, one‐pot chemical modification of P(VDF‐ter‐TrFE‐ter‐CTFE) is reported through the controlled introduction of small fractions of double bonds within the backbone that, very uniquely, decreases the lamellar crystalline thickness while, simultaneously, enlarging the crystalline coherence along the a‐b plane. This increases the polarizability and polarization without affecting the degree of crystallinity or amending the crystal unit cell—undesirable effects observed with other approaches. Specifically, the permittivity increases by >35%, from 52 to 71 at 1 kHz, and ECE improves by >60% at moderate electric fields. At 40 °C, an adiabatic temperature change >2 K is realized at 60 MV m⁻¹ (>5.5 K at 192 MV m⁻¹), compared to ≈1.3 K for pristine P(VDF‐ter‐TrFE‐ter‐CTFE), highlighting the promise of a simple, versatile approach that allows direct film deposition without requiring any post‐treatment such as mechanical stretching or high‐temperature annealing for achieving the desired performance.