Browsing by Author "Chang, Bo-Ren"

Now showing 1 - 3 of 3

Alkyl-Spacer Enhancement in Performance of Light-Emitting Electrochemical Cells
(1970-01-01)
Shiu, Ler-Chun
;
Chang, Bo-Ren
;
Hsiao, Miles C-S
;
Sie, Wu-Sian
;
Wu, Ming-Lun
Synthetic, structural, photophysical, and electrochemical study of [Ir(ppy)(2)(py)(2)](BF4) (1(BF4)) and four di-N-N-bridged complexes of [Ir(ppy)(2)(bpa)](2)(BF4)(2)(2A(BF4)(2)), [Ir(ppy)(2)((cis-bpe))](2)(BF4)(2)(2B(BF4)(2)), [Ir(ppy)(2)(tmp)](2)(BF4)(2)(2C(BF4)(2)), and [Ir(ppy)(2)(bpy)](4)(BF4)(4)(3(BF4)(4)) are described with Hppy = 2-phenylpyridine, py = pyridine, N-N= dipyridyl ligands of 1,2-bis(4-pyridyl)ethane (bpa),cis-1,2-bis(4-pyridyl)ethylene (cis-bpe), 1,3-di(4-pyridyl)propane (tmp), and 4,4'-dipyridine (bpy). Five single-crystal structures of1(PF6),2A(NO3)(2),2A(PF6)(2),2B(PF6)(2), and3(NO3)(4)were determined, supporting the dibridged structures and presence of a variety of stereoisomers. Application of four luminescent complexes,1(BF4),2A(BF4)(2),2C(BF4)(2), and3(BF4)(4), in solid-state light-emitting electrochemical cells (LECs) is reported. The work demonstrates an effective approach to realize efficient LECs based on dibridged di- and multinuclear cationic transition-metal complexes with a suitably long alkyl spacer in the bridging ligand.
Cationic Ir-III Emitters with Near-Infrared Emission Beyond 800 nm and Their Use in Light-Emitting Electrochemical Cells
(2019-04-11)
Chen, Guan-Yu
;
Chang, Bo-Ren
;
Shih, Ting-An
;
Lin, Chien-Hsiang
;
Lo, Chieh-Liang
Solid-state near-infrared (NIR) light-emitting devices have recently received considerable attention as MR light sources that can penetrate deep into human tissue and are suitable for bioimaging and labeling. in addition, solidstate NIR light-emitting electrochemical cells (LECs) have shown several promising advantages over NIR organic light-emitting devices (OLEDs). However, among the reported NIR LECs based on ionic transition-metal complexes (iTMCs), there is currently no iridium-based LEC that displays NIR electroluminescence (EL) peaks near to or above 800 nm. In this report we demonstrate a simple method for adjusting the energy gap between the highest-occupied molecular orbital (HOMO) and the lowest-unoccupied molecular orbital (LUMO) of iridium-based iTMCs to generate NIR emission. We describe a series of novel ionic iridium complexes with very small energy gaps, namely NIR1-NIR6, in which 2,3-diphenylbenzo[g]quinoxaline moieties mainly take charge of the HOMO energy levels and 2,2'-biquinoline, 2-(quinolin-2-yl)quinazoline, and 2,2'-bibenzo[d]thiazole moieties mainly control the LUMO energy levels. All the complexes exhibited NIR phosphorescence, with emission maxima up to 850 nm, and have been applied as components in LECs, showing a maximum external quantum efficiency (EQE) of 0.05% in the EL devices. By using a host-guest emissive system, with the iridium complex RED as the host and the complex NIR3 or NIR6 as guest, the highest EQE of the LECs can be further enhanced to above 0.1%.
Improving color saturation of blue light-emitting electrochemical cells by plasmonic filters
(2017-12-01)
Chiang, Chien-Ming Fan
;
Chang, Bo-Ren
;
Lee, Ya-Ju
;
Sarma, Monima
;
Yang, Zu-Po
In consideration of the advantages of light-emitting electrochemical cells (LECs), it is desired to develop the saturated blue LECs for LEC display, which is hindered by the features of broad emission spectrum and emission peak not short enough. In this study, we demonstrated a novel method to improve blue saturation of the sky-blue LECs by engineering its emission spectrum through the plasmonic filters. These plasmonic filters composed of randomly distributed silver nanoparticles (Ag-NPs) can absorb the green and red emission tail of the sky-blue LECs due to localized surface plasmon resonance (LSPR). The LSPR wavelengths of Ag-NPs are tuned by manipulating the effective refractive index of materials around Ag-NPs through the accurate control of the TiO2 thickness using atomic layer deposition technique. By integrating with the plasmonic filters, the CIE1931 coordinate of the blue LECs can approach to (0.14, 0.22), which is comparable to or even better than the reported bluest values of blue LECs. Combination with the green and red LECs, the color gamut increases from 34% (without filters) to 54% of National Television System Committee (NTSC) color gamut, corresponding to 1.6 times enhancement. In addition, the blue LECs integrated with plasmonic filters still have better efficiency than those of the reported bluest LECs. (C) 2017 Elsevier B.V. All rights reserved.