The absorption behaviour and the emission dynamics of the triplet emitters Ir(ppy)(3) and PtOEP in the singlet emitters, polystyrene (PS) and dicarbazole-biphenyl (CBP), are studied. Thin films are prepared by spin-coating. The host (PS, CBP) - guest (Ir(ppy)3, PtOEP) interaction is investigated. The luminescence behaviour in the case of guest excitation (the excitation frequency in the transparency region of hosts) is compared with the luminescence behaviour ill the case of host excitation (the excitation frequency in the absorption region of hosts). The efficient host-to-guest energy transfer is observed. Additionally, the excitation transfer from PS to CBP and TPD (triphenylamine dimer) is studied.