Crystal-Plane Controlled Spontaneous Polarization of Inorganic Perovskite toward Boosting Triboelectric Surface Charge Density

Abstract

Triboelectric generators (TENGs) have been extensively studied as a new energy for low cost and the universally applicable prospect. Meanwhile, perovskites have been applied in TENG and show a good performance in view of high carrier mobility, long life and dielectric properties. The asymmetry structure of the orthogonal phase CsPbBr₃ perovskite endows it with ferroelectric property and induces the misalignment of the positive and negative charge centers. Herein, the surface energy of halogen doped inorganic CsPbX₃ (X = Cl^-, Br^-) perovskites are theoretically investigated by density functional theory (DFT) calculation, the crystal polarizability of pristine CsPbBr₃ is improved from 0.47 Ry a.u. to 0.52 Ry a.u. (CsPbCl₃), indicating the polarizability of CsPbCl₃ is higher than CsPbBr₃. In addition, the build-in electric field (<i>E</i>_build-in) of perovskite materials can be enhanced by the spontaneous polarization and the aligned dipoles in the <i>E</i>_build-in could further improve the tribo-electrostatic electric field by retaining more triboelectric surface charges. In the end, CsPbCl₃ achieved a power of 3.06 W m^-2 compared to the power of 1.34 W m^-2 of CsPbBr₃. This work focuses on the regulation of crystal planes using spontaneous polarization of perovskite toward achieving a high built-in electric field for enhancing triboelectric surface charge density.