Bright orange and red light-emitting diodes of new visible light excitable tetrakis-Ln-β-diketonate (Ln = Sm3+, Eu3+) complexes. (24th January 2017)

• Record Type: Journal Article
• Authors: Biju, Silvanose; Xu, Liang-Jin; Hora Alves, Marcelo Augusto; Freire, Ricardo Oliveira; Chen, Zhong-Ning
• Is Part Of: New journal of chemistry. Volume 41:Number 4(2017)
• Page Start: 1687
• Page End: 1695
• Publication Date: 2017-01-24
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c6nj03450k
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : A new β-diketonate ligand and its visible light excitable Sm 3+, Eu 3+ -complexes were designed and synthesized; these complexes showed highly efficient photoluminescence and electroluminescence properties. Abstract : The syntheses and luminescent properties of two new visible light excitable lanthanide complexes (NBu4 [LnL4 ]) [L = 1-(4-(9 H -carbazol-9-yl)phenyl)-4, 4, 4-trifluorobutane-1, 3-dione; (Ln = Sm 3+, Eu 3+ )] are described. The (NBu4 [LnL4 ]) complexes exhibit bright photoluminescence at room temperature in solid state with characteristic red and orange emissions of Eu 3+ and Sm 3+ ions, respectively. Photoluminescent overall quantum yield ( ϕ ov ) and lifetime ( τ obs ) values obtained for the complexes are 80 ± 8%, 780 ± 6 μs for (NBu4 [EuL4 ]) and 10% ± 1%, 97 ± 2 μs for (NBu4 [SmL4 ]) ( λ ex = 410 nm) in solid state. RM1 calculations were employed for predicting the ground-state geometry of NBu4 [EuL4 ], which shows that the central Eu 3+ is 8-fold coordinated. Theoretical Judd–Ofelt and photoluminescence parameters predicted for NBu4 [EuL4 ] from this model are in close agreement with the experimental values, proving the efficiency of this theoretical approach implemented in the LUMPAC software (; Web:http://lumpac.pro.br/theory ). LEDs with the general structure ITO/PEDOT:PSS (50 nm)/(NBu4 [LnL4 ]) (5%):CBP (66.5%)–OXD7 (28.5%) (50 nm)/BCP (50 nm)/LiF (1.5 nm)/Al (120 nm), using the two complexes as emitters were fabricated via a simple spin coating technique. The device based on (NBu4 [EuL4 ]) exhibits the maximum brightness of 1234 cd m −2, current efficiency of 3.5 cd A −1, power efficiency of 1.3 lm W −1 and external quantum efficiency of 2.3% with a pure red emission. Whereas, its Sm 3+ analogue shows bright orange emission with a maximum brightness of 831 cd m −2, current efficiency of 1.4 cd A −1, power efficiency of 0.5 lm W −1, and external quantum efficiency of 1.1%.