Polymeric light emitting substance and polymer light emitting device using the same

Abstract

A polymeric light emitting substance having a polystyrene reduced number-average molecular weight of from 10 3 to 10 8 wherein this light emitting substance has in the main chain or side chain a metal complex structure showing light emission from the triplet excited state, and the substance can form a light emitting layer by industrially simple application methods such as a spin coat method, inkjet method, printing method and the like.

1 . A solution comprising an organic solvent and polymer light emitting substance, wherein the polymeric light emitting substance has a polystyrene reduced number-average molecular weight of from 10 3  to 10 8  and the polymeric light emitting substance has in the main chain or side chain a metal complex structure showing light emission from the triplet excited state, wherein the metal complex structure showing light emission from the triplet excited state is represented by the below formula (6): 
       
         
           
           
               
               
           
         
         wherein M represents a metal atom having an atomic number of 50 or more and showing a possibility of the intersystem crossing between the singlet state and the triplet state in this complex by a spin-orbital mutual action; Ar represents a ligand bonded to M via one or more of a nitrogen atom, an oxygen atom, a carbon atom, a sulfur atom and a phosphorus atom, with bonding to a polymer at an arbitrary position; L represents a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, a carboxylate group having 1 to 10 carbon atoms, a diketonate group having 1 to 10 carbon atoms, a halogen atom, an amide group, an imide group, an alkoxide group, an alkylmercapto group, a carbonyl ligand, an arylene ligand, an alkene ligand, an alkyne ligand, an amine ligand, an imine ligand, a nitrile ligand, an isonitrile ligand, a phosphine ligand, a phosphine oxide ligand, a phosphate ligand, an ether ligand, a sulfone ligand, a sulfoxide ligand or a sulfide ligand; m represents an integer of 1 to 5; and o represents an integer of 0 to 5. 
       
     
     
         2 . A solution according to  claim 1 , wherein the light emitting substance has a metal complex structure showing light emission from the triplet excited state in the main chain. 
     
     
         3 . A solution according to  claim 2 , wherein the light emitting substance has a metal complex structure showing light emission from the triplet excited state at least one of the ends of the main chain. 
     
     
         4 . A solution according to  claim 1 , wherein the light emitting substance has a metal complex structure showing light emission from the triplet excited state in the side chain. 
     
     
         5 . A solution according to  claim 4 , wherein an aromatic ring contained in at least one of the ligand of the metal complex structure and an aromatic ring contained in the main chain are connected via a single bond. 
     
     
         6 . A solution according to  claim 1 , wherein the light emitting substance has two or more kinds of the metal complex structure showing light emission from the triplet excited state. 
     
     
         7 . A solution according to  claim 1 , wherein the main chain comprises a conjugated polymer. 
     
     
         8 . A solution according to  claim 1 , wherein at least one ligand contained in the metal complex structure comprises the same structure with a repeating unit contained in the main chain. 
     
     
         9 . A solution according to  claim 1 , wherein the light emitting substance comprising one or more repeating units of the general formula (1) and one or more repeating units having a metal complex structure showing light emission from the triplet excited state: 
       
         
           
           
               
               
           
         
       
       wherein Ar 1  represents an arylene group or a divalent heterocyclic compound group; R 1  and R 2  each independently represent a hydrogen atom, an alkyl group, an aryl group, a monovalent heterocyclic compound group or a cyano group; and n represents 0 or 1. 
     
     
         10 . A solution according to  claim 1 , wherein the light emitting substance comprising one or more repeating units of the formula (2), 
       
         
           
           
               
               
           
         
       
       wherein Ar 2  and Ar 3  each independently represent an arylene group, or a divalent heterocyclic compound group, and Ar 2  does not cross-link to Ar 3 ; R 11  represents an alkyl group, an aryl group, a mono-valent heterocyclic compound group, a group represented by the below formula (3) or (4); the symbol t is an integer from 1 to 4, 
       
         
           
           
               
               
           
         
       
       wherein Ar 4  is an arylene group or a divalent heterocyclic compound group: R 12  represents a hydrogen atom, an alkyl group, an aryl group, a mono-valent heterocyclic group, or a group represented by the below formula (4); Z 1  represents —CR 13 ═CR 14 — or —C≡C—, R 13  and R 14  each independently represents a hydrogen atom, an alkyl group, an aryl group, a mono-valent heterocyclic group, or a cyano group; the symbol u is an integer from 0 to 2; 
       
         
           
           
               
               
           
         
       
       wherein Ar 5  and Ar 6  each independently represents an arylene group or a divalent heterocyclic compound group; R 15  represents an alkyl group, an aryl group, or a mono-valent heterocyclic group; and the symbol v is an integer from 1 to 4. 
     
     
         11 . A solution according to  claim 9 , wherein the light emitting substance comprising one or more repeating units of the formula (5), 
       
         
           
           
               
               
           
         
       
       wherein R 11  means the same as above; R 18  and R 19  represent substituents on aromatic ring of a halogen atom, an alkyl group, an alkenyl group, an aralkyl group, an arylthio group, an arylalkenyl group, a cyclic alkenyl group, an alkoxy group, an aryloxy group, an alkyloxy carbonyl group, an aralkyloxy carbonyl group, an aryloxy carbonyl group, an aryl group, or a mono-valent heterocyclic group; the symbols a and b each independently represent an integer from 0 to 3; and when a or b is 2 or more, R 18  and R 19  are the same or different mutually, which may be connected to form a ring. 
     
     
         12 . A solution according to any one of  claims 9  to  11 , wherein the amount of the repeating units having a metal complex structure showing light emission from the triplet excited state is 0.01 mol % or more and 10 mol % or less based on the total amount of the repeating units of the general formulas (1), (2) and (5), and the repeating units having a metal complex structure showing light emission from the triplet excited state. 
     
     
         13 . A solution according to  claim 1 , wherein M is rhenium atom, osmium atom, iridium atom, platinum atom, or gold atom. 
     
     
         14 . A solution according to  claim 1 , wherein M is samarium atom, europium atom, gadolinium atom, terbium atom or dysprosium atom. 
     
     
         15 . A solution according to  claim 1 , wherein M bonds to at least one carbon atom. 
     
     
         16 . A solution according to  claim 1 , wherein Ar represents a bidentate ligand forming a 5-membered ring by bonding to M via a nitrogen atom, an oxygen atom, a carbon atom, a sulfur atom or a phosphor atom. 
     
     
         17 . A solution according to  claim 1 , wherein Ar represents a bidentate ligand represented by the formula (7), 
       
         
           
           
               
               
           
         
         wherein R 3  to R 10  independently represent a halogen atom, an alkyl group, an alkenyl group, an aralkyl group, an arylthio group, an arylalkenyl group, a cyclic alkenyl group, an alkoxy group, an aryloxy group, an alkyloxy carbonyl group, an aralkyloxy carbonyl group, an aryloxy carbonyl group, or an aryl group; and at least one of R 3  to R 10  is a bonding group to a polymer chain. 
       
     
     
         18 . A solution according to  claim 1 , wherein the organic solvent is selected from chloroform, methylene chloride, dichloroethane, tetrahydrofuran, toluene, xylene, acetone, methyl ethyl ketone, butyl acetate or ethylcellosolve acetate. 
     
     
         19 . A solution according to  claim 1 , wherein the polymeric light emitting substance is dissolved in the solvent in an amount of 0.1% by weight or more. 
     
     
         20 . A method of forming a film, which method comprises removal of the solvent by drying after coating with a solution according to  claim 1 . 
     
     
         21 . A method according to  claim 20 , wherein the method is selected from coating method, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method, spray coating method, screen printing method, flexo printing method, offset printing method or inkjet printing method. 
     
     
         22 . A film formed by removal of the solvent by drying after coating with a solution according to  claim 1 . 
     
     
         23 . A film according to  claim 22 , wherein the thickness is from 1 nm to 1 μm. 
     
     
         24 . A polymer light emitting device comprising at least a light emitting layer between a pair of electrodes composed of an anode and a cathode at least one of which is transparent or semi-transparent wherein the light emitting layer comprises a film according to  claim 22  or  23 . 
     
     
         25 . A flat light source comprising a polymer light emitting device according to  claim 24 . 
     
     
         26 . A segment display comprising a polymer light emitting device according to  claim 24 . 
     
     
         27 . A dot matrix display comprising a polymer light emitting device according to  claim 24 . 
     
     
         28 . A liquid crystal display comprising a polymer light emitting device according to  claim 24  as a back-light.