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

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 beta-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. TOC shows the comparison of doping of Tb3+ and Tb3+ complex in (PEA)4NaInCl8. As a result of doping, PLQY is enhanced to 62% in Tb(L) doping, which is attributed to the efficient energy transfer in the case of Tb(L) doping, whereas, in the case of Tb3+ doping, PLQY is only 3%, because of the large energy gap between host and Tb3+ states.image