Charge carrier dynamics in Cu 2 ZnSn(S/Se) 4 thin film solar cells measured by time resolved terahertz and microwave spectroscopy

We track charge carriers dynamics from femtoseconds to nanoseconds in Cu 2 ZnSn(S/Se) 4 thin films by time resolved terahertz spectroscopy (TRTS) and time resolved micro wave conductivity measurements (TRMC). This includes trapping of photo carriers into band tail states followed by recombination with a time constant of 9.1 ns. The relatively long life time is likely caused by the localization into long living trap states rather than by a low concentration of recombination centers.