In this thesis, we have used a Monte Carlo simulation technique to study the charge carrierrnmobility as a function of charge carrier density and electric _eld in disordered organicrnsemiconducting materials using the lattice model. Our simulations reveal that the chargerncarrier mobility versus charge carrier density at lower charge carrier density and disorderrnis constant. In contrast, at higher disordered and lower charge carrier density, the chargerncarrier mobility increases with charge carrier density. Therefore, the e_ect of the disorderrnparameter (^_ = _rnkBT ) on the charge carrier mobility is more pronounced than the chargerncarrier density at lower charge carrier density. We studied a charge carrier mobility as arnfunction of the electric _eld for the case of the regular grid and spatial disorder latticernsite with di_erent lattice site spacing parameter r and the ratio of localization length tornthe lattice parameter (i. e, _=b). We show that a charge carrier mobility increases withrnan electric _eld for the case of the regular grid and spatial disorder lattice site of lower orrnequal values of lattice site spacing r to the ratio of _=b. But, at a higher value of latticernsite spacing r to the ratio of _=b, the electric _eld dependence of charge carrier mobilityrnfor spatial disordered lattice sites di_ers from that of the regular grid case. We observedrnthat both a localization length and lattice parameter are relevant for the electric _eldrnvariation of charge carrier mobility in both the regular grid and spatial disordered latticernsites at lower or equal values of lattice site spacing r to the ratio of _=b cases. However, atrnhigher values of the lattice site spacing r relative to the ratio of _=b, the only parameterrnrnresponsible for the electric _eld dependence of charge carrier mobility is the localizationrnlength of disordered organic semiconducting materials.