A phosphor compound of Cu m X m+n n wherein: X is a halide, L is a cationic organic ligand, wherein at least two atoms of the ligand are heteroatoms independently selected from the group consisting of N, O and S, one of the at least two atoms is positively charged N and the other of the at least two atoms is coordinated to Cu, m is an integer selected from the group consisting of 1, 2, 3, 4, 5, and 6, n is an integer selected from the group consisting of 1, 2, 3, 4, and 5; and wherein: a) the positively charged N is sp3 hybridized and is bonded to at least three groups independently selected from C1-C10 alkyls, said alkyls substituted with one or more groups selected from halogen, -OR 1, -SR 1, -C 1 -C 4 SR 1, -NO 2, -CN and -NR a R b, wherein R 1 at each occurrence is independently hydrogen or C 1 -C 4 alkyl, and R a and R b are independently hydrogen or C 1 -C 4 alkyl, wherein the other of the at least two atoms is sp 2 hybridized N and coordinates to Cu; or b) the other of the at least two atoms is a ring atom of benzotriazole, said benzotriazole optionally substituted with one or more substituents selected from the group consisting of C1-C10 alkyl, halogen, -OR 1, -SR 1, -C 1 -C 4 SR 1, -NO 2, -CN and -NR a R b, wherein R 1 at each occurrence is independently hydrogen or C 1 -C 4 alkyl, and R a and R b are independently hydrogen or C 1 -C 4 alkyl. X is a halide, L is a cationic organic ligand, wherein at least two atoms of the ligand are heteroatoms independently selected from the group consisting of N, O and S, one of the at least two atoms is positively charged N and the other of the at least two atoms is coordinated to Cu, m is an integer selected from the group consisting of 1, 2, 3, 4, 5, and 6, n is an integer selected from the group consisting of 1, 2, 3, 4, and 5; and wherein: a) the positively charged N is sp3 hybridized and is bonded to at least three groups independently selected from C1-C10 alkyls, said alkyls substituted with one or more groups selected from halogen, -OR 1, -SR 1, -C 1 -C 4 SR 1, -NO 2, -CN and -NR a R b, wherein R 1 at each occurrence is independently hydrogen or C 1 -C 4 alkyl, and R a and R b are independently hydrogen or C 1 -C 4 alkyl, wherein the other of the at least two atoms is sp 2 hybridized N and coordinates to Cu; or b) the other of the at least two atoms is a ring atom of benzotriazole, said benzotriazole optionally substituted with one or more substituents selected from the group consisting of C1-C10 alkyl, halogen, -OR 1, -SR 1, -C 1 -C 4 SR 1, -NO 2, -CN and -NR a R b, wherein R 1 at each occurrence is independently hydrogen or C 1 -C 4 alkyl, and R a and R b are independently hydrogen or C 1 -C 4 alkyl. a) the positively charged N is sp3 hybridized and is bonded to at least three groups independently selected from C1-C10 alkyls, said alkyls substituted with one or more groups selected from halogen, -OR 1, -SR 1, -C 1 -C 4 SR 1, -NO 2, -CN and -NR a R b, wherein R 1 at each occurrence is independently hydrogen or C 1 -C 4 alkyl, and R a and R b are independently hydrogen or C 1 -C 4 alkyl, wherein the other of the at least two atoms is sp 2 hybridized N and coordinates to Cu; or b) the other of the at least two atoms is a ring atom of benzotriazole, said benzotriazole optionally substituted with one or more substituents selected from the group consisting of C1-C10 alkyl, halogen, -OR 1, -SR 1, -C 1 -C 4 SR 1, -NO 2, -CN and -NR a R b, wherein R 1 at each occurrence is independently hydrogen or C 1 -C 4 alkyl, and R a and R b are independently hydrogen or C 1 -C 4 alkyl.