“…Known structure modifications include i.a. : dopants introduced in Cu sublattice (Nb [18], Fe [19,20,21,22], Cd [23], Pb [24], Zn [20,25,26], Ni [20,27,28], Mn [29,30,31,32], Co [31], Cr [33], Mg [34,35], Ge and Sn [36]); dopants introduced in Sb sublattice (Bi [37,38], Te [39,14], Sn [40,41]); dopants introduced in S sublattice (Se [42,43]); sulfur deficiency [44]; excess Cu in structural voids [45,46] and substitution of Sb for Cu [47]. Some of those aforementioned were simultaneous substitutions of more than one element.…”