Sulfonium salt photoinitiator, preparation method therefor, photocurable composition comprising sulfonium salt photoinitiator, and use thereof

A sulfonium salt photoinitiator, wherein the sulfonium salt photoinitiator has a structure represented by formula (I):

• wherein Ar1 is an aryl group or a substituted aryl group;
• Ar2 is
• wherein R6 and R6′ are each independently a C1 to C20 linear or branched alkyl group, a C3 to C20 cycloalkyl group, a C1 to C10 alkyl group substituted with a C3 to C8 cycloalkyl group, a C3 to C8 cycloalkyl group substituted with a C4 to C20 alkyl group, a C6 to C20 aryl group, a C3 to C20 heterocyclic group, or a C1 to C10 alkyl group substituted with a C6 to C14 aryl group, and n3 and n4 are each independently an integer of 0 to 4;
• R1′ is a C1 to C20 linear or branched alkyl group, a C3 to C20 cycloalkyl group, a C1 to C10 alkyl group substituted with a C3 to C8 cycloalkyl group, a C3 to C8 cycloalkyl group substituted with a C4 to C20 alkyl group, a C6 to C20 aryl group, a C2 to C20 heterocyclic group, or a C1 to C10 alkyl group substituted with a C6 to C14 aryl group;
• and Q is a single bond, O, S,
• and R3, R4, and R5 are each independently an organic substituent;
• R1 represents a C1 to C20 linear or branched alkyl group, a C3 to C20 cycloalkyl group, a C1 to C10 alkyl group substituted with a C3 to C8 cycloalkyl group, a C3 to C8 cycloalkyl group substituted with a C4 to C20 alkyl group, a C6 to C20 aryl group, a C2 to C20 heterocyclic group, or a C1 to C10 alkyl group substituted with a C6 to C14 aryl group;
• R2 and R2′ are each independently a C1 to C20 linear or branched alkyl group, a C3 to C20 cycloalkyl group, or a C1 to C10 alkyl group substituted with a C3 to C8 cycloalkyl group, and n1 and n2 each independently represent an integer of 0 to 4;
• M is a single bond, O, S,
• and R3, R4, and R5 are each independently an organic substituent;
• Y− represents an inorganic anion or an organic anion.