Photoinitiator compounds comprising both a photoactive moiety and an amine functionality, bonded to a polyhedral oligomeric silsesquioxane, which photoinitiator is represented by formula (1) or (1′) wherein n is 2m; m is an integer of 2 to 30; the sum of n′+a is an integer 4-60; n′ is an even-numbered integer; a is an even- or uneven-numbered integer; and for example different A C1-C12alkyl, or a photoactive moiety Q1, or a group of formula (2); E for example is a direct bond, L is linear or branched C1-C3alkylene, preferably propylene; R1 and R2 for example are a photoactive moiety Q, or C2-20alkyl; Q is for example a group of formula (4); Z2 is for example C1-C6alkylene which is unsubstituted or substituted by one or more OR6; and R6, R12, R13 and R14 for example are hydrogen; are especially suitable as low-migrating photoinitiators.