Toward a multifunctional monolithic device based on pyroelectricity and the electrocaloric effect of thin antiferroelectric HfxZr1-xO2 films

Antiferroelectric HfxZr1-xO2 (HZO, x=0.1-0.3) films are reported herein as new Si-compatible materials for monolithic devices for pyroelectric energy harvesting, electrocaloric cooling, electrostatic energy storage, and infrared sensing. Hf0.2Zr0.8O2 and Hf0.3Zr0.7O2 films could work as pyroelectric energy harvesters using the Olsen cycle with the harvested energy densities of 11.5 and 5.7 J cm(-3) cycle(-1), which are similar to 7.6 and similar to 3.7 times larger than the largest value ever reported. The electrocaloric effect (ECE) of HZO films was also firstly examined, and the maximum Delta T values of the Hf0.2Zr0.8O2 and Hf0.3Zr0.7O2 films were 13.4 (at 307 K) and 9.8 K (at 448 K), respectively. The wide temperature range for the large ECE of the HZO films was highly promising for the actual cooling cycle with large reversible work values. Moreover, the large capacitance of the HZO films due to the field-induced phase transition between the poled and anti-poled states can be used for electrostatic energy storage and high-charge capacitors. The k(2) and F-v values, which are the figures of merit for conventional pyroelectric energy conversion and infrared detection for thermal imaging, of the Hf0.2Zr0.8O2 film were 24.4 x 10(-3) and 32.0 x 10(-2) M-2 C-1, respectively, which prove that Hf0.2Zr0.8O2 is also a promising material for these applications. (C) 2014 Elsevier Ltd. All rights reserved.