Processes for purifying diketopyrrolopyrrole copolymers

Abstract

Transistors comprising semiconducting layers of diketopyrrolopyrrole (DPP) copolymers are disclosed. Processes for purifying DPP copolymers are also disclosed. An organic phase containing the DPP copolymer is treated with an aqueous ammonia solution and then with a palladium scavenger. The DPP copolymer is then isolated, and has a very low palladium content. The resulting DPP copolymer has high mobility.

1 . A transistor, comprising:
 a substrate in contact with a gate electrode and a gate dielectric layer;   a semiconducting layer, a source electrode, and a drain electrode;   wherein the source electrode and the drain electrode are in contact with the gate dielectric layer;   wherein the gate dielectric layer separates gate electrode from the semiconducting layer, the source electrode, and the drain electrode; and   wherein the semiconducting layer contains a diketopyrrolopyrrole copolymer having low palladium content, formed by:   receiving an organic phase containing the diketopyrrolopyrrole copolymer;   treating the organic phase with an aqueous ammonia solution at a temperature of from about 50° C. to about 80° C.;   treating the organic phase with a palladium scavenger; and   isolating the diketopyrrolopyrrole copolymer from the organic phase to obtain the diketopyrrolopyrrole copolymer having low palladium content.   
     
     
         2 . The transistor of  claim 1 , wherein the diketopyrrolopyrrole copolymer has a palladium content of less than 150 ppm and a total metal content of less than 300 ppm. 
     
     
         3 . The transistor of  claim 1 , wherein the diketopyrrolopyrrole copolymer having low palladium content has a weight average molecular weight of 20,000 or higher when measured using high-temperature gel permeation chromatography in trichlorobenzene at 140° C.; or
 wherein the diketopyrrolopyrrole copolymer having low palladium content has a polydispersity index (PDI) of less than 4.0. 
 
     
     
         4 . The transistor of  claim 1 , wherein the organic phase includes an organic solvent selected from the group consisting of anisole, toluene, ethylbenzene, o-xylene, m-xylene, p-xylene, trimethylbenzene, mesitylene, tetrahydronapthalene, and mixtures thereof. 
     
     
         5 . The transistor of  claim 1 , wherein the palladium scavenger is sodium diethyldithiocarbamate, ethylenediamine tetraacetic acid (EDTA), or ethylene diamine; or
 wherein the palladium scavenger is a polymer containing a monomer selected from the group consisting of styryl sulfonic acid, vinyl pyridine, styryl thiol, and mercaptoethyl acrylate; or   wherein the palladium scavenger includes a functional group selected from the group consisting of thiourea, benzyl amine, imidazolylalkyl, aminoalkyl, thioalkyl, imidazolylalkyl amino, mercaptophenyl amino, and aminoethyl amino.   
     
     
         6 . A transistor, comprising:
 a substrate in contact with a gate electrode and a gate dielectric layer;   a semiconducting layer, a source electrode, and a drain electrode;   wherein the semiconducting layer is upon the gate dielectric layer and separates the source electrode and the drain electrode from the gate dielectric layer; and   wherein the semiconducting layer contains a diketopyrrolopyrrole copolymer having low palladium content, formed by:   receiving an organic phase containing the diketopyrrolopyrrole copolymer;   treating the organic phase with an aqueous ammonia solution at a temperature of from about 50° C. to about 80° C.;   treating the organic phase with a palladium scavenger; and   isolating the diketopyrrolopyrrole copolymer from the organic phase to obtain the diketopyrrolopyrrole copolymer having low palladium content.   
     
     
         7 . The transistor of  claim 6 , wherein the aqueous ammonia solution contains from about 2% to about 30% ammonia (v/v). 
     
     
         8 . The transistor of  claim 6 , wherein the organic phase is treated with the aqueous ammonia solution for a time period of 30 minutes to 90 minutes. 
     
     
         9 . The transistor of  claim 6 , wherein the diketopyrrolopyrrole copolymer is isolated from the organic phase by extraction, precipitation, and vacuum filtration. 
     
     
         10 . The transistor of  claim 6 , wherein the organic phase containing the diketopyrrolopyrrole copolymer is prepared by:
 reacting a reaction mixture that contains a diketopyrrolopyrrole monomer, an aryl comonomer, a palladium catalyst, an organic phase, and an aqueous phase, so that the diketopyrrolopyrrole copolymer is formed; and   separating the organic phase containing the diketopyrrolopyrrole copolymer from the reaction mixture.   
     
     
         11 . The transistor of  claim 10 , wherein the reacting occurs at a temperature of from 60° C. to 120° C. 
     
     
         12 . The transistor of  claim 10 , wherein the reacting occurs for a time period of from about 6 hours to about 36 hours. 
     
     
         13 . A process for obtaining a diketopyrrolopyrrole copolymer having low palladium content, comprising:
 receiving an organic phase containing the diketopyrrolopyrrole copolymer;   treating the organic phase with an aqueous ammonia solution;   treating the organic phase with a palladium scavenger at a temperature of from about 40° C. to about 80° C.; and   isolating the diketopyrrolopyrrole copolymer from the organic phase to obtain the diketopyrrolopyrrole copolymer having low palladium content.   
     
     
         14 . The process of  claim 13 , wherein the palladium catalyst is present in the amount of from about 1 mole % to about 5 mole % of the reaction mixture. 
     
     
         15 . The process of  claim 13 , wherein the aqueous phase contains from 1 to 10 molar equivalents of a base, and wherein the volume ratio of organic phase to aqueous phase in the reaction mixture is from about 1:1 to about 5:1. 
     
     
         16 . The process of  claim 10 , wherein the diketopyrrolopyrrole monomer has the structure of Formula (I): 
       
         
           
           
               
               
           
         
         wherein Ar 1  and Ar 2  are independently aryl, substituted aryl, heteroaryl, or substituted heteroaryl; 
         R 1  and R 2  are independently hydrogen, alkyl, substituted alkyl, poly(ethylene glycol), poly(propylene glycol), aryl, substituted aryl, heteroaryl, or substituted heteroaryl; and 
         Y 1  and Y 2  are independently halogen. 
       
     
     
         17 . The process of  claim 10 , wherein Ar 1  and Ar 2  are independently selected from the group consisting of thiophene, furan, thienothiophene, and selenophene. 
     
     
         18 . The process of  claim 10 , wherein the aryl comonomer is an aryl boronate having the structure of Formula (III):
   BE-Ar″-BE  Formula (III)
   wherein BE is selected from the group consisting of:   
       
         
           
           
               
               
           
         
         and wherein Ar″ is selected from the group consisting of: 
       
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         wherein each R′ is independently selected from hydrogen, alkyl, substituted alkyl, poly(ethylene glycol), poly(propylene glycol), aryl, substituted aryl, heteroaryl, substituted heteroaryl, halogen, alkoxy, alkylthio, trialkylsilyl, —CN, or —NO 2 ; and X is C or Si. 
       
     
     
         19 . The process of  claim 10 , wherein the palladium catalyst has the structure of Formula (IV): 
       
         
           
           
               
               
           
         
         wherein R a  is H, —N(CH 3 ) 2 , or —CF 3 . 
       
     
     
         20 . The process of  claim 17 , wherein R a  is —N(CH 3 ) 2 .