Structural defects and chemical impurities exist in organic semiconductors acting as trap centers for the excited states. This work presents a novel analytical model to calculate the trapping and detrapping rates between two Gaussian density of states. Miller-Abrahams rate and Fermi-Dirac statistics are employed in this model. The introduction of effective filled and empty sites for correlated bands greatly simplifies the expression of recombination rate. A technology computer-aided design simulator was used to simulate the donor-like traps in an organic semiconductor DPP-DTT based thin-film transistor, showing good agreement with the measured transfer characteristic.