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

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 (Ebuild-in) of perovskite materials can be enhanced by the spontaneous polarization and the aligned dipoles in the Ebuild-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.