Time‑correlated single‑photon counting (TCSPC) technique is powerful to measure the weak light signal. The basic principle behind TCSPC is the photoelectric effect in which an electrical charge is released by absorbing a photon. Compare to the traditional strategy detecting analog photogenerated voltage, the TCSPC technique counts the single electron pulse created by single photon, which means its sensitivity can be up to single-photon level as its name implies. In fact, TCSPC technique has been successfully employed to detect the transient/burst photoluminescence (PL) in many research fields, and transient spectrometer is common equipment in many labs.
Dr. Xianfeng Qiao and Prof. Dongge Ma at South China University of Technology (SCUT), China, are interested in device physics of organic optoelectronics/spintronics devices. Specifically, they pay attention on both transient PL and electroluminescence (EL) profiles, which together provide a wealth of information about how devices work. So they improved their spectrograph and combined it with a pulse generator. This improvement enables their transient spectrometer to record both transient PL and EL signals. With this improved spectrometer, energy transfer mechanisms and exciton evolution in organic light emitting diodes could be in-situ investigated. The researchers also proved that the superior sensitivity of TCSPC technique is helpful for extracting mobility. Detail information could be found in work entitled "Improved transient electroluminescence technique based on time-correlated single-photon counting technology for evaluating organic mobility" (published on Apr. 20, 2022) in Frontiers of Optoelectronics. This work will inspire those who want to measure weak pulse EL and meanwhile they have a transient spectrometer. A simple and cost-effective solution is provided in this work.
