Warm White Light-Emitting Diodes Based on a Novel Orange Cationic Iridium(III) Complex

Abstract

A novel orange cationic iridium(III) complex [(TPTA)2Ir(dPPOA)]PF6 (TPTA: 3,4,5-triphenyl-4H-1,2,4-triazole, dPPOA: N,N-diphenyl-4-(5-(pyridin-2-yl)-1,3,4-oxadiazol-2-yl)aniline) was synthesized and used as a phosphor in light-emitting diodes (LEDs). [(TPTA)2Ir(dPPOA)]PF6 has high thermal stability with a decomposition temperature (Td) of 375 °C, and its relative emission intensity at 100 °C is 88.8% of that at 25°C. When only [(TPTA)2Ir(dPPOA)]PF6 was used as a phosphor at 6.0 wt % in silicone and excited by a blue GaN (GaN: gallium nitride) chip (450 nm), an orange LED was obtained. A white LED fabricated by a blue GaN chip (450 nm) and only yellow phosphor Y3Al5O12:Ce3+ (YAG:Ce) (1.0 wt % in silicone) emitted cold white light, its CIE (CIE: Commission International de I’Eclairage) value was (0.32, 0.33), color rendering index (CRI) was 72.2, correlated color temperature (CCT) was 6877 K, and luminous efficiency (ηL) was 128.5 lm∙W−1. Such a cold white LED became a neutral white LED when [(TPTA)2Ir(dPPOA)]PF6 was added at 0.5 wt %; its corresponding CIE value was (0.35, 0.33), CRI was 78.4, CCT was 4896 K, and ηL was 85.2 lm∙W−1. It further became a warm white LED when [(TPTA)2Ir(dPPOA)]PF6 was added at 1.0 wt %; its corresponding CIE value was (0.39, 0.36), CRI was 80.2, CCT was 3473 K, and ηL was 46.1 lm∙W−1. The results show that [(TPTA)2Ir(dPPOA)]PF6 is a promising phosphor candidate for fabricating warm white LEDs.

Preparation of Red Phosphor Sr2Si5N8: Eu2+ by Pellet Method and Its Optical Characteristics

“…The nonradiative energy transfer can be concretely expressed by the critical transfer distance (R c ), which is the distance between the activators at the quenching concentration. The R c can be roughly estimated by the Blasse formula, as shown in Equation ( 1) [3]:…”

“…At present, phosphor-converted white light-emitting diodes (PC-WLEDs) have attracted increasing attention due to their unique properties of longer life, lower power consumption, and more environment-friendly characteristics [1][2][3][4][5], compared with current commercial white LEDs devices, which are prepared by combining yellow phosphor Y 3 Al 5 O 12 : Ce 3+ and blue LED chips [6]. However, PC-WLEDs usually exhibit higher color temperature and poor color rendition due to the lack of a red light component [7,8].…”

Bis-Tridendate Ir(III) Polymer-Metallocomplexes: Hybrid, Main-Chain Polymer Phosphors for Orange–Red Light Emission

“…Of these two families, tris-cyclometalated iridium(III) complexes have been more prominently featured in the literature, as they offer facile modification routes and color tunability [10][11][12][13]. Such tris-bidentate iridium polyimine complexes, like bis [2-(4,6-difluorophenyl) pyridinato-C2,N](picolinato)iridium(III)(FIrpic), tris [2-phenylpyridinato-C2,N]iridium(III)(Ir(ppy) 3 ), bis(4-phenyl-thieno [3,2-c]pyridinato-C2,N)(acetylacetonato)iridium(III)(PO-01), and bis(2-methyldibenzo [f,h]quinoxaline)(acetylacetonate)iridium(III)(Ir(MDQ) 2 (acac)), have been extensively used in light-emitting devices with high EQEs [14,15].…”

A Heat-Stimulated Luminous Fiber Using Heat-Sensitive Green TF-G Pigment

“…For example, a luminous fiber with white light can be fabricated using SZSO, SAO, and YOS by adjusting their ratios [6,7,8,9,10]. A luminous fiber with polychromatic light has many applications in sensors and optical devices [11,12]. …”