Application of a novel cationic iridium(iii) complex as a red phosphor in warm white light-emitting diodes

Abstract

Warm white light-emitting diodes were obtained when the red-emitting iridium(iii) complex was added in LEDs based on blue GaN chips and YAG:Ce.

Versatile Homoleptic Naphthyl‐Acetylide Heteronuclear [Pt2M4(CC‐Np)8] (M = Ag, Cu) Phosphors for Highly Efficient White and NIR Hybrid Light‐Emitting Diodes

“…Therefore, renewed interest has emerged in OPs, leading to hybrid LEDs (HLEDs) . This involves Cd‐based quantum dots (Cd‐QDs), ionic transition metal complexes, fluorescent proteins, organic small molecules, molecular organic frameworks (MOFs), and perovskites . In general, HLEDs have achieved efficiencies up to 130 lm W −1 and a high color quality with x / y International Commission on Illumination (CIE) color coordinates of 0.30‐3/0.30‐3, CRI above 90, and easy‐to‐modulate CCT from 2700 to 6500 K .…”

“…The main bottleneck is still the device stability with white HLEDs featuring lifetimes ranging from seconds to less than 200 h with handful exceptions that includes coordination complexes like iridium(III) complexes (1000 h) and hybrid luminescent silica nanoparticles (>2500 h), as well as small molecules like perilenedimide (700 h) . The scarceness of suitable low‐energy emitting OPs has its origin in i) the poor match between high‐energy excitation/absorption bands and efficient emission with a large Stoke shift, ii) the prominent increase of the phosphor‐matrix temperature under device operation, leading to efficient thermal‐assisted photoquenching and photobleaching under ambient conditions, and iii) the need of environmentally friendly and nontoxic compounds …”

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

“…However, because the main emission of YAG:Ce is in the greenish yellow region, aforementioned commercial WLEDs have low color rendering index (CRI) and high correlated color temperature (CCT). Due to the absence of a red light component in their spectra, the light emitted from such WLEDs is cold white light [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. Two approaches have been developed to overcome this drawback.…”

“…Hence, the development of new efficient red phosphors for warm WLEDs based on blue chips is very important and urgently needed. Up to now, besides many inorganic phosphors (such as CaSiAlN 3 :Eu 2+ [ 10 ], InP/GaP/ZnS quantum dots [ 11 ], Mn 4+ activated fluorides [ 5 , 12 , 13 ], and so on), many organic luminescent materials (such as organic metal complexes [ 14 , 15 , 16 , 17 , 18 ], polymers [ 19 ] and small-molecule fluorescent dyes [ 20 , 21 ], and so on) have also been used as red luminescent materials in WLEDs.…”

“…Recently, cationic iridium(III) complexes have also been used as luminescence conversion materials (i.e., phosphors) in inorganic LEDs [ 15 , 18 , 29 , 30 ], and exhibited good performances. In 2013, C.-Y.…”