We begin the analysis of transport of charge carriers in organic semiconductors, focusing on the depen-rndence of charge carriers mobility on density, external electric _eld and temperature. We start with thernformulation of the main relationships that provides the current density as a function of conductivity andrnelectrical _eld. Conjugated polymer _lms are composed of carbon-based molecular chains, which arernheld together by weak van der Waals interactions. Such type of weak intermolecular interaction givesrnrise to a soft and exible molecular system. This exibility character and its other properties, whichrninclude electronic properties, have made the material attractive for scienti_c investigations since it hasrnshown possible applications in electronic devices such as light emitting diodes, _eld-e_ect transistorsrn(FETs), and solar cells.rnThe electronic states in disordered semiconductors are localized and the transport of charge carriersrnoccurs by hopping between the localized states. The hopping transitions between localized states and thernexchange of electrons between localized and extended states form a variety of complex phenomena thatrndetermine the charge carrier transport. we discuss a variety of transport phenomena known as hoppingrntransport mechanisms. The description of the relationship between current density and charge carrierrndensity in disordered organic-semiconductors is complicated by the e_ects of di_usion and a charge-rncarrier mobility that depends on the disorder nature of the material, charge concentration, electric _eldrnand temperature. With the help of computer simulations, we study the mobility of charge carriersrnand their corresponding di_usive character at di_erent temperatures. The ratio between mobility andrndi_usion parameters is derived for a Gaussian like density of states. This steady-state analysis isrnexpected to be applicable to a wide range of organic materials (polymers or small molecules) as it reliesrnon the existence of quasi-equilibrium only. Our analysis shows that there is an inherent dependence ofrnthe transport in disordered organic-materials on the charge carrier density.rnWe investigate the e_ects of disorder on the external electric _eld and charge carrier density de-rnpendence of the mobility in disordered organic semiconductor with a Gaussian shape of the density ofrnstates. The results we found are compared with recently published numerically exact expressions forrnthe dependence of the charge-carrier mobility on the carrier density, temperature and the electric _eldrnin such organic semiconductor materials.rnWe consider the MillerAbrahams expression to describe the hopping rate of charge carriers andrnemploy kinetic Monte Carlo simulation methods to generate data from which we can analyze a chargerncarrier mobility as a function of applied electric _eld, temperature, localization length, and energeticrniiirndisorder parameters. Based on our results, we discuss the e_ects of these parameters on charge carrierrnmobility. Our results show the importance of the energetic disorder parameter and localization lengthrnon the e_ects of temperature dependence on charge carrier mobility, and we also evaluate the value ofrnlocalization length that has been mostly considered as 0.1a, where a is the lattice parameter. Finally,rnthe temperature dependence is markedly di_erent in single crystals and in disordered materials. Inrnsingle crystals, the hole and electron mobilities generally decrease with temperature.