TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The compound(s) having triplet state is phosphorescent compound(s) of formula (X), with concentration of 1.10-4 mol/l, sensitizer compound capable of absorbing radiation at frequency (a) and/or emissive compound. At least one sensitizer compound is capable of transferring energy to at least one emissive compound. The total content of all phosphorescent compounds and all compounds comprising terminal unsaturated carbon-carbon bond(s) in the composition is 100 mol%. The compound(s) capable of reacting with singlet oxygen is chosen from compounds of formulae: R-X-R1 (I), R3-Y'(-XR)(-R2)-R1 (II), R-X(-R2)-R1 (III), R3-Y'(-PEG)(-R2)-R'1 (IV), R"'1-O-X1(=O)(-O-R"'2)-O-R (VI), R-O-X"(=O)(=O)-O-R"1 (VII), R"'2-O-X2(-O-R"'1)-O-R (VIII), R"'3-O-X3(-O-R)(-O-R"'2)-O-R"'1 (IX), and compounds of formulae (XA)-(XD). The compound (II) is chosen from 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, 6-hepten-1-ol, 7-octen-1-ol, 1,2-di-(3-buten-1-yloxy)ethane, 1,2-di-(4-penten-1-yloxy)ethane, 1,2-di-(5-hexen-1-yloxy)ethane, 1,2-di-(6-hepten-1-yloxy)ethane, 1,2-di-(7-octen-1-yloxy)ethane, 1,2-di-(3-buten-1-yloxy)benzene, 1,2-di-(4-penten-1-yloxy)benzene, 1,2-di-(5-hexen-1-yloxy)benzene, 1,2-di-(6-hepten-1-yloxy)benzene, 1,2-di-(7-octen-1-yloxy)benzene, 1,3,5-tri-(3-buten-1-yloxy)benzene, 1,3,5-tri-(4-penten-1-yloxy)benzene, 1,3,5-tri-(5-hexen-1-yloxy)benzene, 1,3,5-tri-(6-hepten-1-yloxy)benzene and 1,3,5-tri-(7-octen-1-yloxy)benzene.X,X1=P;R,R'1=allyl, 3-buten-1-yl, 4-penten-1-yl, 5-hexen-1-yl, 6-hepten-1-yl, 7-octen-1-yl, 8-nonen-1-yl, 9-decen-1-yl or 10-undecen-1-yl;R1,R2=H or R;PEG=oligoethylene glycol or polyethylene glycol having 2-99 ethylene glycol units;Y'=1-6C alkyl or phenyl;R2,R3=H, COOR, X'R4, allyl, 3-buten-1-yl, 4-penten-1-yl, 5-hexen-1-yl, 6-hepten-1-yl, 7-octen-1-yl, 8-nonen-1-yl, 9-decen-1-yl or 10-undecen-1-yl;X'=N or P;R,R4=allyl, 3-buten-1-yl, 4-penten-1-yl, 5-hexen-1-yl, 6-hepten-1-yl, 7-octen-1-yl, 8-nonen-1-yl, 9-decen-1-yl or 10-undecen-1-yl;X"=S;R"1,R"'1,R"'2,R"'3=3-8C alkyl, phenyl, allyl, 3-buten-1-yl, 4-penten-1-yl, 5-hexen-1-yl, 6-hepten-1-yl, 7-octen-1-yl, 8-nonen-1-yl, 9-decen-1-yl or 10-undecen-1-yl;X2=B;X3=Si;n,m,o=1-20;andp=2 or more.