Ternary Halide Perovskites for Highly Efficient Solution-Processed Hybrid Solar Cells

Hybrid organic–inorganic perovskite materials have attracted substantial attention as photovoltaic light abosorbers due to their outstanding physical properties and outstanding power conversion efficiencies (PCEs). Structural variation of perovskite absorbing materials has proven to be an effective route to improve device performance; notably, tuning of the halide anion composition constitutes a key approach to control material properties. In this work, we demonstrate a bridged ternary halide approach to process materials with the formula MAPbI 3– y – x Br y Cl x, which yields high PCEs in planar, p–i–n type heterojunction perovskite solar cells. This ternary halide perovskite system improves device performance from 12 to 16% when an optimal concentration of 10% Br is incorporated into the binary Cl–I systems via increases in short-circuit current density, open-circuit voltage, and the fill factor, which arise from the formation of homogeneous crystal domains and a subtle widening of the optical band gap. Remarkably, the ternary halide perovskite devices exhibited approximately 100% internal quantum efficiency (IQE) throughout their entire absorption range (400–800 nm).