Time‑correlated single‑photon counting (TCSPC) technique is a powerful way to measure the weak light signals. The basic principle behind TCSPC is the photoelectric effect in which an electrical charge is released by absorbing a photon. Compared to the traditional strategy of detecting analog photogenerated voltage, the TCSPC technique counts the single electron pulse created by single photons, which means its sensitivity can be up to single-photon level as its name implies. In fact, the TCSPC technique has been successfully employed to detect the transient/burst photoluminescence (PL) in many research fields, and the transient spectrometer is common equipment in many labs.