Here, I(t) is the time-dependent UC emission intensity, [ 3 A*] is the annihilator triplet concentration, t is time, and b is a dimensionless parameter indicating what fraction of triplets that initially decay by second-order channels, as defined by Equation . In other words, b represents a system's TTA efficiency (with a possible maximum of 100%), and FTTA may be calculated as b/2 given that these are evaluated at identical experimental conditions.