Effective　surface　passivation　is　pivotal　for　achieving　high　performance　in　crystalline　silicon　(c　c-　Si)　solar　cells.　However,　many　passivation　techniques　in　solar　cells　involve　high　temperatures　and　cost.　Here,　we　report　a　low-cost　and　easy-to-implement　sulfurization　treatment　as　a　surface　passivation　strategy.　By　treating　p-　type　c-　Si　(p　p-　Si)　wafers　with　(NH4)2S　4　)　2　S　solution,　sulfur　can　be　introduced　onto　the　surface　and　passivate　the　dangling　bonds　by　forming　an　Si-S　bond.　Sulfurization　also　contributes　to　a　higher　negative　fixed　charge　at　the　p-　Si/Al　2　O　3　interface　and,　thus,　better　field-effect　passivation.　Due　to　the　improved　passivation,　sulfurization　effectively　enhances　hole　selectivity,　evidenced　by　the　substantially　improved　open-circuit　voltage　and　efficiency　of　solar　cells.　Eventually,　by　employing　sulfurization　in　hole-selective　contacts,　remarkable　efficiencies　of　19.85%　and　22.01%　are　attained　for　NiOx-　x-　and　MoOx-based　x-based　passivating　contact　c-　Si　solar　cells,　respectively.　Our　work　highlights　a　promising　sulfurization　strategy　to　enhance　surface　passivation　and　hole　selectivity　for　dopant-free　c-　Si　solar　cells.