Recently reported colloidal lead halide perovskite quantum dots (gDs) with tunable photoluminescence (PL) wavelengths covering the whole visible spectrum and exceptionally high PL quantum yields (gYs, 50-90%) constitute a new family of functional materials with potential applications in light-harvesting and -emitting devices. By transient absorption spectroscopy, we show that the high PL gYs (similar to 79%) can be attributed to negligible electron or hole trapping pathways in CsPbBr3 QDs: similar to 94% of lowest excitonic states decayed with a single-exponential time constant of 4.5 +/- 0.2 ns. Furthermore, excitons in CsPbBr3 QDs can be efficiently dissociated in the presence of electron or hole acceptors. The half-lives of electron transfer (ET) to benzoquinone and subsequent charge recombination are 65 5 ps and 2.6 +/- 0.4 ns, respectively. The half-lives for hole transfer (HT) to phenothiazine and the subsequent charge recombination are 49 +/- 6 ps and 1.0 +/- 0.2 ns, respectively. The lack of electron and hole traps and fast interfacial ET and HT rates are key properties that may enable the development of efficient lead halide perovskite Us-based light-harvesting and -emitting devices.