Inducing 2D Structure at Grain-Boundary via Triazinane Molecular Modification to Improve Stability of Inverted Perovskite Solar Cells

Active layers of p-i-n organic-inorganic hybrid perovskite solar cells (PSCs) are passivated by star-shape, multifunctional triazinane molecules, cyanuric acid (CA), and Tris(dibutylhydroxy- benzyl)isocyanuric acid (TPCA). The most interesting is that CA is used as a bulk additive is able to induce a two-dimensional (2D) structure at grain boundaries (GBs) of the perovskite when excess PbI2 is present. TPCA is also important to use as a perovskite surface modifier and to reduce the defects in perovskite layer further. The reduced ideality factors, enhanced photoluminescence, and prolonged lifetimes all indicate suppression of non-radiative recombination. The combination of the two substantially improves fill-factors and open-circuit voltages of the devices. This leads to markedly enhanced stabilities of the devices.