Development And Optoelectronic Property Of White-light-emitting Ln³⁺-containing Metallopolymer Materials

With the progressive advance of white organic lighting-emitting diodes?WOLED?in applications of background light source,panel display and solid-state lighting,organo-Ln³⁺-resourced white-light-emitting materials have been of considerable interest,due to the unique characters of Ln³⁺-centered narrow line-like emission,long phosphorescent lifetime and lager stokes shift.To date,despite the significant opportunity to small molecule organo-Ln³⁺-complexes,the‘bottleneck'problems to their WOLEDs lie in low thermal stability,poor mechanical property and high cost from vacuum-evaporation fabrication.Conceivably,the circumvention to these problems,to some extent,can rely on a solution-processing procedure through doping an organo-Ln³⁺-complex into a polymeric matrix for cost-effective and large-area white polymer light-emitting diodes?WPLEDs?.However,this strategy still suffers from the detrimental adventures of device's performance instability and inferior efficiency arisen from phase separation,chromophores-aggregated self-quenching and ¹T-¹T annihilation.In this thesis,an alternative approach can borrow from the grafting of the small molecule organo-Ln³⁺-complexes into a polymeric matrix for the formation of Ln³⁺-containing metallopolymer material with direct white-light.Toward this end,the small-molecular organo-Ln³⁺-complexes can molecularly dispersed into the polymer matrix in favor of the homogeneity.Moreover,using the obtained Ln³⁺-containing and white-light-emitting metallopolymer as the emitting layer,simplified WPLEDs with both low-cost and superior electroluminescent performance are expected.The contents in detail are listed as follows.Firstly,based on the design of series of styryl-functionalized small-molecule Ln³⁺-complex monomers ?:[Ln?TTA?₃?4-VB-PBI?]?Ln=La,1;Eu,2;Tb,3;Gd,4;the?-diketone ligand HTTA=2-thenoyltrifluoroacetonate;theancillaryligand4-VB-PBI=1-?4-vinylbenzyl?-2-?pyridin-2-yl?-1H-benzo[d]imidazole?,the copolymerization of red-light complex monomer 2,green-light complex monomer 3 or blue-light complex monomer 4 with MMAwasrealizedtogivethedoping-metallopolymer Poly?MMA-co-2?@Poly?MMA-co-3?@Poly?MMA-co-4?with direct white-light(CIE x=0.323,y=0.298;CCT=6937 K;CRI=77;???_PL=10.5%).In contrast,through their terpolymerization,another kind of Eu³⁺-Tb³⁺-Gd³⁺-grafted metallopolymer with ultra-high CRI and higher efficiency white-light emission(CIE x=0.322,y=0.331,CCT=5979 K,CRI=94,???_PL=17.8%)was also successfully obtained.Secondly,within the series of styryl-modified small-molecule Ln³⁺-complex monomers ?:[Ln?DBM?₃?4-VB-PBI?]?Ln=La,5;Eu,6;Tb,7;Gd,8;HDBM=dibenzoylmethane?and ?:[Ln?tba-PMP?₃?4-VB-PBI?]?Ln=La,9;Eu,10;Tb,11;Gd,12;Htba-PMP=1-phenyl-3-methyl-4-?tert-butylacetyl?-5-pyrazolone?,the complex monomer 6 with red light and complex monomer 11 with green light were selected the primary dichromatic resources.Through their copolymerization with one of monomers of MMA,ST and NVK,different types of Eu³⁺-Tb³⁺-containing metallopolymers with desirable photo-physical properties were obtained.Especially for that PVK-supported Eu³⁺-Tb³⁺-containing metallopolymer Poly?NVK-co-6-co-11?,its attractive white-light emission is characteristic of the color compensation from blue-light of PVK,besides the activation of PVK to Tb³⁺and/or Eu³⁺F?ster energy transfer.More importantly,the first example of WPLED(CIE x=0.335,y=0.364,CCT=5410 K,CRI=89;L_max=280 cd/m²,CE_max=2.5 cd/A,PE_max=1.06 lm/W and EQE_max=1.65%)based on that PVK-supported and Eu³⁺-Tb³⁺-grafted metallopolymer was successfully realized.Thirdly,in dependence of the molecular design of styryl-functionalized small molecule Ln³⁺-complex monomers ?:[Ln?TTA?₃?4-VB-FBI?]?Ln=La,13;Eu,14;Tb,15;Gd,16;4-VB-FBI=1-?4-vinylbenzyl?-2-?furan-2-yl?-1H-benzo[d]imidazole?andV:[Ln?tba-PMP?₃?4v-2,2'-bpy?]?Ln=La,17;Eu,18;Tb,19;Gd,20;4v-2,2'-bpy=2-?pyridin-2-yl?-5-?4-vinylphenyl?pyridine?,both the doping-type material PVK/14/19 and the grating-type material Poly?NVK-co-14-co-19?were developed,and their trichromatic white-light is integrated from red-light of complex monomer 14,green-light of complex monomer 19 and blue-light of PVK.Moreover,in comparison to the electroluminescent performance(CIE x=0.314,y=0.340,CCT=6561 K,CRI=93;L_max=121 cd/m²,CE_max=1.10 cd/A,PE_max=0.31 lm/W and EQE_max=0.65%)of the WPLED from PVK/14/19,the formation of grafted metallopolymer Poly?NVK-co-14-co-19?renders a new platform to WPLED with the distinctively improved performance(CIE x=0.308,y=0.355,CCT=6585K,CRI=90;L_max=196 cd/m²,CE_max=1.88 cd/A,PE_max=1.12 lm/W and EQE_max=3.67%).At last,in avoidance of the complicated Tb³⁺to Eu³⁺energy transfer,the PVK-supported and Sm³⁺-containing metallopolymer Poly?NVK-co-21-co-[4V-PI-DMA]?was developed,in which,the direct white-light is color-tuned from the cooperation of the cyan light from small organic dye 4V-PI-DMA?4-?1-?4-vinylbenzyl?-2,11b-dihydro-1H-phenanthro[9,10-d]imidaz-ol-2-yl?-N,N-dimethylbenzenamine?and the orange light of Sm³⁺-complex monomer[Ln?TTA?₃?4-VB-PBI?]?Ln=Sm,21?.Actually,besides the exclusive sensor for Cu²⁺ion?2.42×10^-66 M?,the hybrid material is beneficial to WPLED with the desirable electroluminescent performance(CIE x=0.324,y=0.301,CCT=5930 K,CRI=83;L_max=285 cd/m²,CE_max=4.86 cd/A,PE_max=1.92 lm/W and EQE_max=3.24%).