In this study, a steady state and time‐dependent exciton diffusion model including singlet and triplet excitons coupled with a modified Poisson and drift‐diffusion solver to explain the mechanism of hyper triplet–triplet fusion (TTF) organic light‐emitting diodes (OLEDs) is developed. Using this modified simulator, various characteristics of OLEDs, including the current‐voltage curve, internal quantum efficiency, transient spectrum, and electric profile are demonstrated. This solver can also be used to explain the mechanism of hyper‐TTF‐OLEDs and analyze the loss from different exciton mechanisms. Furthermore, we perform additional optimization of hyper‐TTF‐OLEDs that increases the internal quantum efficiency by ≈33% (from 29% to 40%).