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 in the presence of an ionic liquid are reported. While strongly emissive at 535 nm [Photoluminescence Quantum Efficiency (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.