Effects of Hydroiodic Acid Concentration on the Properties of CsPbI(3) Perovskite Solar Cells

[Image: see text] Inorganic cesium lead triiodide (CsPbI(3)) perovskite materials are becoming increasingly attractive for use in perovskite/silicon tandem solar cells, due to their almost ideal band gap energy (E(g)) of about 1.7 eV. To be useful as photovoltaic absorbers, the CsPbI(3) must form the cubic or black phase (α-CsPbI(3)). To do so at relatively low temperatures, hydroiodic acid (HI) is required as a solution additive. This paper demonstrates CsPbI(3) perovskite solar cells with an efficiency of 6.44%, formed using a HI concentration of 36 μL/mL. This value is higher than the previous most commonly used HI additive concentration. Herein, by undertaking a systematic study of the HI concentration, we demonstrate that the structural, morphological, optical, and electrical properties of CsPbI(3) solar cells, processed with this HI additive concentration, are superior.