Perovskite solar cells (PSCs) have generated a lot of interest in the scientific horizon due to their high-power conversion efficiency (PCE) and low cost. In the current study, we assessed the photovoltaic efficiency of Li-doped electron transport layer (ETL) PSCs through parameter variation in the absorber layer, electron transport layer (ETL), and ETL-absorber interface. We utilized a solar simulation tool known as solar cell capacitance simulator (SCAPS), which is based on Poisson and the semiconductor equations to optimize the performance of the HTL-free device. The method in enhancing the performance of the solar cell was studied thoroughly by varying the thickness, defect density (Nt), and doping concentration (NA) of the absorber, thickness and doping concentration (ND) of ETL, and the ETL/absorber defect density. The performance of the simulated device is significantly influenced by the thickness of the absorber layer, defect density of the absorber layer, doping concentration of the absorber layer, thickness of the ETL layer, and doping concentration of the ETL layer. We obtained a PCE of 26.72%, fill factor (FF) of 85.53%, current density (Jsc), and voltage (Voc) of 22.265 mA/cm2 and 1.387 V, respectively for the Li-TiO2 ETL-based optimized device. Additionally, the effects of series resistance, shunt resistance and temperature on the optimized device were evaluated and found that they affect the performance of the device. Finally, the photovoltaic (PV) characteristics obtained through this thorough investigation are compared with previously published theoretical and experimental studies using Li-TiO2 as ETL. As a result, our thorough simulation opens up a fruitful research path for the fabrication of inexpensive, highly efficient, and stable perovskite solar cell.