Over the last decade,the power conversion efficiency of hybrid organic-inorganic perovskite solar cells (PSCs) has increased dramatically from 3.8％ to 25.2％.This rapid progress has been possible due to the accurate control of the morphology and crystallinity of solution-processed perovskites,which are significantly affected by the concentration of the precursor used.This study explores the influence of precursor concentrations on the performance of printable hole-conductor-free mesoscopic PSCs via a simple one-step drop-coating method.The results reveal that lower concentrations lead to larger grains with inferior pore filling,while higher concentrations result in smaller grains with improved pore filling.Among concentrations ranging from 0.24-1.20 M1),devices based on a moderate strength of 0.70 M were confirmed to exhibit the best efficiency at 16.32％.