The mobilities of electrons and holes determine the applicability of any semiconductor, but their individual measurement remains a major challenge. Here, we show that time resolved terahertz spectroscopy TRTS can distinguish the mobilities of minority and majority charge carriers independently of the doping type and without electrical contacts. To this end, we combine the well established determination of the sum of electron and hole mobilities from photo induced THz absorption spectra with mobility dependent ambipolar modeling of TRTS transients. The method is demonstrated on a polycrystalline Cu2ZnSnSe4 thin film and reveals a minority electron mobility of 128 cm2 V s and a majority hole carrier mobility of 7 cm2 V s in the vertical transport direction relevant for light emitting, photovoltaic and solar water splitting devices. Additionally, the TRTS analysis yields an effective bulk carrier lifetime of 4.4 ns, a surface recombination velocity of 6 104 cm s and a doping concentration of ca. 1016 cm 3, thus offering the potential for contactless screen novel optoelectronic material
