The effects of dielectric and conducting nanofiller size, loading, and electric field on bipolar charge injection, transport, and recombination (or electroluminescence) through amorphous polymer are studied. Versions of 3D particle-in-cell model based on the classical electrical double layer representation are used to treat the conducting and dielectric nanoparticles. Metal–polymer charge injection assumes Schottky emission and Fowler–Nordheim tunneling, migration through field-dependent Poole–Frenkel mobility, and recombination with Monte Carlo selection based on collision probability. A boundary integral equation method is used for solution of the Poisson equation coupled with a second-order predictor–corrector scheme for robust time integration of the equations of motion. The stability criterion of the explicit algorithm conforms to the Courant–Friedrichs–Levy limit. Trajectories for charge that traverse the film are curvilinear paths that meander through the interspaces of the interaction zone. Compared to dielectric nanofillers, composite films with conducting nanofillers have: larger peaks and higher steady-state amplitudes for both injected currents and electrode E fields; <1/6 of the attached charge fraction; >2x of the conduction charge fraction; >2x of the recombined charge fraction; all charge fractions change very rapidly at sizes below 10nm; much higher loading of 21vol.% versus 2vol.%; and higher leakage conductivities of 0.5×10−14S/cm and 0.75×10−14S/cm with bipolar and unipolar charge, respectively, where the value for the dielectric nanofiller is ∼0.2×10−14S/cm. Effective permittivities computed using a new energy conservation method is shown to have excellent agreement compared with established Lichtenecker, Bruggeman, and Maxwell-Garnett mixing rules. Computed stored energies show monotonic increase with dielectric fillers and a peak at 25vol.% for conducting fillers which may be attributed to the competing effects of higher energy with increasing field modification and lower energy with decreasing binder volume.