First-principles calculations and device characterizations of formamidinium-cesium lead triiodide perovskite crystals stabilized by germanium or copper

Abstract To avoid formation of the photo-inactive δ -phase formamidinium-cesium lead triiodide, copper or germanium was added to perovskite compounds stabilize photoactive α -phase. It found that substitution by (Ge) (Cu) provided stabilization in present work. The first-principles molecular dynamics calculations indicated displacements formamidinium molecules were suppressed Ge doping. X-ray diffraction results Cu doping could be effective for suppression phase transition from -