Increased Efficiency for Perovskite Photovoltaics via Doping the PbI₂ Layer

Perovskite solar cells offer tremendous potential for simple and low-cost solution-based fabrication with high power conversion efficiency. This work focused on adding an optimized amount of additive tetra- n -butylammonium triiodide (TBAI 3 ) into the precursor PbI 2 layer to improve the performance of perovskite solar cells. UV–vis absorption spectra exhibited an enhancement in the absorbance of perovskite films while AFM images showed smoother MAPbI 3 film after adding TBAI 3 . X-ray diffraction (XRD) measurements indicated that TBAI 3 acted as a polar Lewis base, forming an adduct with the Lewis acid Pb 2+, increasing PbI 2 solubility, and enhancing crystal growth of perovskite. Current density–voltage ( J – V ) characteristics and transient photocurrent measurements showed that the TBAI 3 dopant achieved an increase in short circuit current density ( J sc ) and open circuit voltage ( V oc ) and a decrease in the charge transport time compared to the reference cell without any additive. Perovskite solar cell efficiency was enhanced from 11.18% to 14.85% by adding TBAI 3 dopant to the PbI 2 precursor.