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 (TBAI₃) into the precursor PbI₂ 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 MAPbI₃ film after adding TBAI₃. X-ray diffraction (XRD) measurements indicated that TBAI₃ acted as a polar Lewis base, forming an adduct with the Lewis acid Pb²⁺, increasing PbI₂ solubility, and enhancing crystal growth of perovskite. Current density-voltage (J-V) characteristics and transient photocurrent measurements showed that the TBAI₃ 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 TBAI₃ dopant to the PbI₂ precursor. (Chemical Equation Presented).