From Blue to White: Sustainable Luminescent Metal Organic Framework for Hybrid Light-Emitting Diodes

Abstract

Hybrid light-emitting diodes based on photon down-converting filters with metal organic frameworks (MOFs) are mainly restricted to cross-breed materials (i.e., nonemissive MOFs host and guest emitters) due to the lack of highly photostable and luminescent MOFs (LMOFs). This work reports a sustainable and cost-effective blue-emitting Zn-based MOF with the ligand 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)ethene (Zn-2-LMOF) and their host:guest hybrids with Rhodamine B emitter RhB@LMOF toward blue- and white-emitting hybrid light-emitting diodes (HLEDs). Zn-2-LMOF features blue emission (λem = 480 nm) with impressive photoluminescence quantum yield (ϕ) values of 50% (powder) and 70% (polystyrene coatings). Likewise, hybrid RhB@LMOF features a white emission with ϕ of 30–40% in polystyrene coatings. They lead to blue (Zn-2-LMOF; x/y CIE color coordinates of 0.28/0.47) and white (RhB@LMOF; x/y CIE color coordinates of 0.31/0.32) HLEDs with stabilities of 20 and 45 h at 50 mA on-chip under ambient operation, respectively. Though this device performance is average in HLEDs, the device degradation is mainly attributed to the photoinduced oxidation of the ligand in the MOF structure that further leads to the RhB degradation; a key information for future developments in luminescent MOFs.