Optical studies of 2D Hybrid Lead Iodide Perovskites

2D organic-inorganic hybrid perovskites have recently attracted substantive interest because of their outstanding optoelectronic characteristics and stability under ambient conditions. These compounds consist of alternating organic and inorganic layers that form natural multiple quantum wells. We have investigated the photoexcitations in (C₆H₅C₂H₂NH₃)₂PbI₄ films using photoinduced absorption (PA) and electroabsorption (EA) spectroscopies. We found a strong PA band at 0.15 eV that is due to long-lived free carrier absorption that is caused by the Rashba-splitting in this material. From the EA spectrum we found that the exciton binding energy is about 200 meV, whereas the continuum shows Franz-Keldysh oscillation that unambiguously reveals the band-edge energy.