Unveiling Piezoelectric Property of a CsPbC1₃ Microcrystal for Flexible Nanogenerator Design

Inorganic (cesium) metal halide perovskites have shown great potential for incorporation into flexible nanogenerators, solar cells, and wearable electronic devices. Their low-temperature solution processability, flexibility, and piezoelectric properties have uniquely placed them over century-old ceramic piezoelectric materials. Piezoelectric properties of a material are dependent on crystal orientation and could vary in their two-dimensional thin films or three-dimensional bulk microstructure. This study shed light on the intrinsic piezoelectric property of a single microcrystal <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(3× 2.5μ m²)</tex> of cesium lead chloride <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(CsPbCl₃)</tex> . Piezoelectric properties of the microcrystals were revealed using state-of-the-art piezo response force microscopy (PFM) technique. Our measured piezoelectric charge constant <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(d₃₃)of 19 pCN⁻¹</tex> is found to be analogous to their thin film form, and higher than lithium niobate <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(LiNbO₃)</tex> ceramic, and piezoelectric voltage coefficients <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(g₃₃)of 43.3 mVmN⁻¹</tex> is higher than that of Pb (Zr, Ti) <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O₃</tex> (PZT). The synthesized microcrystals were further dispersed in polydimethylsiloxane (PDMS) to make a flexible nanogenerator. With a force of 4.2 N, the NG with 5 wt. % <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CsPbCl₃</tex> in the PDMS produced a peak voltage of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">~ 40V</tex> current of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">~ 4.1μ A</tex> , and power of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">~ 111μ W</tex> . This result is among the best few NGs made with organic/inorganic halide perovskite materials. This work will inspire the exploration of novel piezoelectric materials to design efficient nanogenerators for harnessing ambient vibration energies, thereby realizing self-powering nano/microdevices.