High Luminescence in Layered Double Perovskite via Formation of Terbium Intercalation Complex

Abstract As the field of perovskite emerges, doping presents an optimistic way to upgrade the functionalities of these materials and improve the photoluminescence quantum yield (PLQY). While doping is well‐explored in perovskites, it has received less attention in layered double perovskites (LDPs). Doping with lanthanides is particularly interesting for these wide bandgap materials because of their narrow and intense luminescence spectra. Here, the doping of (PEA)₄NaInCl₈ LDP (PEA = Phenylethylammonium) with Tb³⁺ and complex of Tb³⁺ with hexafluoroacetylacetonate (hfa) is studied, i.e., tetrakis β‐diketonate complex. In both cases, energy transfer from host to dopant leading to photoluminescence (PL) emission due to Tb³⁺ f‐f transitions is observed. However, in the case of Tb³⁺ doping, sensitization is not very efficient due to the nonideal alignment of energy levels of the host and resonance acceptor energy levels of Tb³⁺. Whereas, doping of (PEA)₄NaInCl₈ with Tb³⁺ in the form of hfa complex, provides a more ideal energetic environment for the efficient energy transfer from host to Tb³⁺ in the LDP matrix, resulting in a 20‐fold enhancement in the luminescence efficiency. The doping of Tb³⁺ and Tb³⁺ complex in LDP sets the foundation for a new approach for the synthesis of LDPs‐lanthanide host‐guest systems for high PLQY.