Anomalous electro-absorption in the low-temperature phase of (C10H21NH3)2PbI4

Electro-absorption (EA) spectra have been measured on thin films of (C10H21NH3)2 PbI4, a layered perovskite-type material, over the lowest-energy exciton region at 300 K [room-temperature (RT) phase] and 77 K [low-temperature (LT) phase]. An anomalous EA signal has been observed for the LT phase, while the RT-phase EA signal exhibits a behavior characteristic of a normal exciton. The LT-phase EA signal with an anomalous line shape and phase may be related to a domain-like structure of unknown origin.