Time-correlated single-photon counting (TCSPC) is a common technique to measure photoluminescence decays in the time domain. In principle, single-photon events are detected and their time of arrival is correlated to the laser pulse, which was used for excitation of the sample. Exciting the sample by using a pulsed laser source with a high repetition rate, this process can be repeated many times so that a photon distribution over time is built up. Photons emitted by the sample are detected with a high-gain photo-multiplier and the time concerning the excitation pulse is measured. By counting many events a histogram of the photon distribution in time is built up.