Over the past few years, hybrid perovskite solar cells (PSCs) have drawn a lot of interest due to their remarkable properties. Nonetheless, the lead toxicity and instability issues make it difficult for PSC to become commercially viable. The less toxic and stable nature of silver bismuth iodide (Ag–Bi–I) makes it a promising material for photovoltaic applications. Nevertheless, almost all these solar cells are constructed with a mesoporous architecture that includes costlier and unstable hole-transport layers (HTLs) in addition to noble metal electrodes. Herein, we fabricate the carbon-based AgBiI₄ solar cell without HTL and by introducing HCl acid as an additive, the film quality has been enhanced  and the  solar  cell  displays a power  conversion efficiency  (PCE) of 1.04% and  J_sc  of 3.91 mA cm^-2. It  was observed that the quality of the film has been boosted by the utilization of HCl as a chlorine source. Thus, our findings pave the way for the cost-efficient and easy fabrication of lead-free solar cells.