Doping of a Zn-MOF with Eu3+ and Tb3+ for application in the manufacture of a WLED

Abstract

A new blue light-emitting molecular–organic framework namely FQUNAM-MOF (1) was synthesized in a simple way using formic acid and zinc nitrate as precursors. In the present work, the potential of 1 as an efficient antenna for terbium and europium 3+ ions was evaluated at different dopant ratios. The compounds labelled Eu³⁺_0.3−nTb³⁺_n@1 where n = 0.15, 0.18, and 0.21, are isostructural and their luminescence properties were studied in detail. Excellent energy transfer occurs from the MOF-excited energy levels towards the ⁵D₄ state in Tb³⁺, unlike Eu³⁺ where the sensibilization predominantly arises from the ⁵D₄ terbium state. These compounds exhibit a high solid-state quantum yield (QY) from 23.4 to 48.5%, higher than the reported values, and they show thermal stability at high temperatures. Additionally, a white light-emitting device (WLED) was prepared using a resin in which 20% (w/w) of the Eu_0.09Tb_0.21@1 compound (48.5% QY) was added. It displayed a white-cold light emission colour according to the Commission Internationale de I’Éclairage (CIE) classification (applying current values of 10, 30, and 100 mA). These materials contribute to the emerging field of molecular–organic frameworks for the development of new efficient and stable lighting sources.