Ultrafast Carrier Drift Transport Dynamics in CsPbI₃ Perovskite Nanocrystalline Thin Films

We study the early time carrier drift dynamics in CsPbI3 nanocrystal thin films with a sub 25 ps time resolution.Prior totrapping, carriers exhibit band-like transport characteristics, whichis similar to those of traditional semiconductor solar absorbers includingSi and GaAs due to optical phonon and carrier scattering at high temperatures.In contrast to the popular polaron scattering mechanism, the CsPbI3 nanocrystal thin film demonstrates the strongest opticalphonon scattering mechanism among other inorganic-organic hybridperovskites, Si, and GaAs. This ultrafast dynamics study establishesa foundation for understanding the fundamental carrier drift propertiesthat drive perovskite nanocrystal optoelectronics.