A capsule suitable for oxygen and temperature sensing contains:i) at least one first sensitizer compound being capable of energy transfer to triplet oxygen,ii) at least one compound being capable of reacting with and inactivating singlet oxygen,iii) at least one second sensitizer compound being capable of absorbing radiation at a second frequency v2 and of emitting light at a fourth frequency v4,iv) at least one emitter compound, wherein the at least one second sensitizer compound is capable of transferring energy to the at least one emitter compound and wherein the at least one emitter compound, after obtaining energy transferred from the at least one second sensitizer compound, is capable of emitting light at a third frequency v3, wherein the following equation is fulfilled: v3>；v2,wherein the upper energy limit of the first triplet energy band of the first sensitizer compound is lower than the lower energy limit of the second triplet energy band of the second sensitizer compound and lower than the lower energy limit of the third triplet energy band of the emitter compound, and wherein the third triplet band of the emitter compound at least partially overlaps with the second triplet energy band of the second sensitizer compound.
