In　the　perovskite　solar　cells　(PSCs),　traps　of　the　perovskite　film　or　interface　are　the　research　focus,　which　can　severely　hinder　charge　transfer　and　benefit　charge　recombination,　thus　weakening　the　photoelectric　performance　of　the　devices.　Herein,　a　Thioacetamide　(TAA)　interfacial　layer　is　used　to　passivate　the　traps　of　PSCs.　Comparing　to　the　control　device　(17.65%),　the　TAA-based　solar　cells　can　achieve　an　enhanced　efficiency　of　19.14%.　It　is　found　that　the　passivation　caused　by　TAA　occurs　through　the　interactions　of　sulfur　in　TAA　with　undersaturated　Pb　in　perovskite　and　Ti4+　in　TiO2,　resulting　in　a　faster　and　more　efficient　charge　transfer　and　a　greatly　reduced　trap　density　from　3.36 × 1016 cm−3　to　1.93 × 1016 cm−3.　It　is　shown　that　the　modification　method　using　TAA　may　be　helpful　for　passivating　traps　and　obtaining　excellent　photoelectric　properties　of　PSCs.　©　2021　The　American　Ceramic　Society