An Interplay Role between Ammonium and Halide Anions as Additives in Perovskite CH3NH3PbI3

Methylammonium lead trihalide perovskites have emerged as attractive materials for solar cell applications. The major eminence of this materials can be crystallized via various solution methods to produce the solid state of thin films. However, the crystallinity of perovskite depends on the composition of perovskites. Here, we study NH4Cl and NH4Br as precursor additives for improving crystallinity of perovskites. Perovskite was synthesized by mixing precursor solutions of CH3NH3I and Pb(Ac)2with or without additives NH4Cl and NH4Br using the one-step spin-coating method. By characterizing the thin films using XRD, SEM and UV-Vis spectrophotometer, we found anion Cl and Br performed an important role toward crystallinity, morphology, and optical absorption of perovskites, respectively. Meanwhile, ammonium has assisted to facile remove the residual DMSO solvent confirmed by FTIR. These results shed light on using ammonium halides as potentially dual side additives in the synthesis of perovskites.