Exceptional Fine Structure in the Photoluminescence Excitation Spectra of Perovskites: Evidence for Rashba Splitting?

In this communication, distinctive photoluminescence excitation (PLE) spectral properties in films of methylammonium lead tribromide grown on yttrium-stabilized zirconium oxide (YSZ) in the presence of an ionic liquid are reported. While strongly emissive at 535 nm (PLQE values above 60%), the associated PLE spectrum shows an interesting series of distinct peaks, one set with an average energy separation of ~200 meV, the other set with ~100 meV separation. The origins of this unusual splitting are discussed, including the possibility of Rashba splitting in such perovskite films.