The Sun provides Earth with a greenhouse gas free source of energy that exceeds the annual energy consumption by orders of magnitude. Current solar cell technology limits the percentage of harvested solar energy that can be used to generate electricity; this is why new concepts and materials for photovoltaics are being explored. Lead-halide perovskite solar cells offer the chance for low-cost high-performance devices. As a result of the rapid technological development, perovskite solar cells have reached power conversion efficiencies exceeding 22% at the laboratory stage, which is comparable to established thin-film technologies. The success of lead-halide perovskites is based on the impressive charge transport and remarkably low recombination rates for a solution-processable semiconductor along with high optical absorption. Low transport and recombination losses in combination with a thin light absorbing layer are essential for a high-performance and low-cost solar cell. Despite their success in numerous optoelectronic devices, some of the most fundamental material and physical properties of lead-halide perovskites are still under intense debate. The work included in this thesis is dedicated to the investigation of the photophysical properties of lead-iodide perovskites. The photophysics is discussed for three processes, here introduced in order of their occurrence, following photo-excitation of the material: the formation of polarons on a sub-picosecond timescale, the slow cooling of charge carriers on the order of hundred picoseconds and the radiative recombination in the nanosecond time range. The first chapters introduce solar energy, the theoretical background, and methodology followed by a summary of the experimental work performed during this thesis work. Using time-resolved THz spectroscopy, the formation of polarons was observed and quantified. Polarons in tetragonal CH3NH3PbI3 and CH(NH2)2PbI3 are formed within 0.4 picoseconds independent of the temperature. The formation of polarons resolves fundamental questions of the origin of the moderate charge carrier mobility and low radiative recombination. Along with the formation of polarons, charge carriers cool on two different timescales. The majority of the charge carriers cools within a few picoseconds. A smaller fraction of charge carriers cools much slower, requiring tens of picoseconds to reach the band minima, two orders of magnitude slower than in GaAs. The slow cooling of charge carriers was investigated using transient absorption spectroscopy. The recombination of charge carriers was investigated on two different timescales using time-resolved photoluminescence spectroscopy. Concomitant to the slow cooling of charge carriers, high-energy photon emission with a photon energy in excess of up to 0.15 eV compared to the band edge emission was observed. The influence of different processing techniques to the recombination of charge carriers was investigated on a nanosecond timescale. As a result of the different processing conditions, the density of trap states changes along with the morphology of the perovskite film. These results provide new insights into the fundamental properties, such as polaron formation and carrier cooling in lead-halide perovskites, and link the extrinsic characteristics, for instance trap density, to photophysical processes like the radiative recombination.