In the exponential growth of perovskite solar cells (PSCs), there remains certain concerns regarding the wide-range incident photons absorption. The doubly graded lead-free absorber in the PSC has been recommended for solving these problems. The absorber material in the PSC is based on the lead-free as well as tin-based perovskite i.e., CH3NH3SnI3, that is one of the precarious parameters due to the non-toxic behavior as well as the lower band gap of 1.3 eV that can be useful in broad visible absorption spectrum than the traditional CH3NH3PbI3 layer. Furthermore, the quantum efficiency (QE) as well as the power conversion efficiency (PCE) in the double-graded configuration of the PSC can be improve. The outcomes of the present numerical simulations examine the solar cells' single and double grading strategy. Further, we use a novel approach of HTL-free PSC, that can lower the manufacturing cost and the defectivity. The present work compares single and double-grading Perovskite Absorber Layer (PAL) for obtaining high PCE. The results are exciting as the highest open-circuit voltage (VOC) of 0.965V, higher short-current density (JSC) of 35.26 mA/cm2 and high fill factor (FF) of 86.40% in the doubly-graded PSC shows a much-optimized PCE of nearly 29.35% that can be convenient for fabricating much efficient PSC device. © 2023 Elsevier Ltd.