Poly(ether imide) Sandwiched by Ultrathin Hafnium Oxide films for High-temperature Capacitive Applications

Polymer film capacitors play an important role in advanced electrical and electronic devices. Recently, many industrials require capacitors operating at the temperature as high as
$\mathbf{200~^{\circ} {C}}$
, while polymer dielectric materials suffer from significantly increased conduction loss under elevated temperatures. To address this issue, we deposited ultrathin wide-bandgap
$\mathbf{HfO}_{2}$
films onto both sides of Poly(ether imide) (PEI) substrate using atomic layer deposition (ALD) and investigated the leakage current, breakdown strength and energy storage performance of
$\mathbf{HfO}_{2}/\mathbf{PRI}/\mathbf{HfO}_{2}$
composites at
$\mathbf{200~^{\circ} \mathrm{C}}$
. Experiment results show that a dense and uniform layer of amorphous
$\mathbf{HfO}_{2}$
forms on the surface of PEI. The resultant composites exhibit reduced leakage current, enhanced breakdown strength, enhanced charge-discharge efficiency and discharged energy density compared with neat PEI. Moreover, thicker
$\mathbf{HfO}_{2}$
coating layers are more effective in suppressing the conduction loss at elevated temperatures.