Organic Photosensitive Devices Comprising a Squaraine Containing Organoheterojunction and Methods of Making Same

Abstract

An organic photosensitive optoelectronic device comprising at least one Donor-Acceptor heterojunction formed from a squaraine compound of formula I: wherein each of Ar 1 and Ar 2 is independently chosen from an optionally substituted aromatic group. The organic optoelectronic device described herein may also comprise a Donor-Acceptor heterojunction that is formed from at least two different squaraine compounds. A method of making the disclosed device, which may include at least one sublimation step for depositing the squaraine compound, is also disclosed.

1 . An organic photosensitive optoelectronic device comprising at least one Donor-Acceptor heterojunction formed from a squaraine compound of formula I: 
       
         
           
           
               
               
           
         
       
       wherein each of Ar 1  and Ar 2  is independently chosen from an optionally substituted aromatic group. 
     
     
         2 . The organic photosensitive optoelectronic device of  claim 1 , wherein each of Ar 1  and Ar 2  is independently chosen from a group of formula II: 
       
         
           
           
               
               
           
         
       
       wherein each X is independently chosen from H, alkyl, alkoxy, halide, and hydroxy; and Y is chosen from H or an optionally substituted amino group. 
     
     
         3 . The organic photosensitive optoelectronic device of  claim 2 , wherein at least one X group of formula II is hydroxy. 
     
     
         4 . The organic photosensitive optoelectronic device of  claim 2 , wherein each Y group is independently chosen from a group represented by the formula NR 1 R 2 , wherein each of R 1  and R 2  is independently chosen from H or an optionally substituted alkyl or aryl group. 
     
     
         5 . The organic photosensitive optoelectronic device of  claim 4 , wherein at least one of R 1  and R 2  is a substituted alkyl group. 
     
     
         6 . The organic photosensitive optoelectronic device of  claim 1 , wherein the squaraine compound is represented by formula III: 
       
         
           
           
               
               
           
         
       
       wherein each X is independently chosen from H, alkyl, alkoxy, halide, and hydroxy; and each of R 1  and R 2  is independently chosen from an optionally substituted alkyl or aryl group. 
     
     
         7 . The organic photosensitive optoelectronic device of  claim 6 , wherein at least one X group of the compound of formula III is hydroxy. 
     
     
         8 . The organic photosensitive optoelectronic device of  claim 1 , wherein said device is a solar cell or photodetector. 
     
     
         9 . The organic photosensitive optoelectronic device of  claim 8 , wherein said device is a solar cell, and wherein said at least one donor-acceptor heterojunction is formed at an interface of a material comprising said squaraine compound of formula I and a material chosen from a donor or an acceptor. 
     
     
         10 . The organic photosensitive optoelectronic device of  claim 1 , further comprising at least one electrode or charge transfer layer comprising transparent collecting electrodes. 
     
     
         11 . The organic photosensitive optoelectronic device of  claim 10 , further comprising a buffer layer between said transparent conducting oxide and the squaraine. 
     
     
         12 . The organic photosensitive optoelectronic device of  claim 11 , wherein said buffer layer comprises at least one of copper phthalocyanine (CuPc) and N,N′-di-1-naphthyl-N,N′-diphenyl-1,1′-biphenyl-4,4′ diamine (NPD). 
     
     
         13 . The organic photosensitive optoelectronic device of  claim 12 , further comprising a layer of C 60  immediately adjacent to the squaraine compound. 
     
     
         14 . The organic photosensitive optoelectronic device of  claim 1 , wherein each of Ar 1  and Ar 2  is independently chosen from a group represented by the following formula V: 
       
         
           
           
               
               
           
         
       
       wherein each of rings A and B are optionally substituted C 4 -C 8  rings, which are fused to form a bicycle saturated or unsaturated ring system comprising 6-14 carbon atoms. 
     
     
         15 . The organic photosensitive optoelectronic device of  claim 14 , wherein the squaraine compound of formula I is chosen from 2,4-Di-3-guaiazulenyl-1,3-dihydroxycyclobutenediylium dihydroxide and a salt thereof. 
     
     
         16 . The organic photosensitive optoelectronic device of  claim 1 , wherein the squaraine compound of formula I is chosen from 2,4-Bis [4-(N,N-dipropylamino)-2,6-dihydroxyphenyl; 2,4-Bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl; and salts thereof. 
     
     
         17 . The organic photosensitive optoelectronic device of  claim 1 , wherein each of Ar 1  and Ar 2  is independently chosen from a group represented by formula VI: 
       
         
           
           
               
               
           
         
       
       wherein n is chosen from 0, 1, 2, 3, 4, 5, and 6; and Z represents a linking group. 
     
     
         18 . The organic photosensitive optoelectronic device of  claim 1 , wherein the squaraine compound of formula I is not symmetric. 
     
     
         19 . The organic photosensitive optoelectronic device of  claim 1 , wherein the squaraine compound of formula I is amorphous. 
     
     
         20 . The organic optoelectronic device of  claim 19 , wherein the Donor-Acceptor heterojunction is formed from at least two different squaraine compounds. 
     
     
         21 . The organic optoelectronic device of  claim 1 , wherein said Donor-Acceptor heterojunction is a mixed or bulk heterojunction. 
     
     
         22 . A method of forming an organic photosensitive optoelectronic device, said method comprising forming at least one Donor-Acceptor heterojunction formed from a squaraine compound of formula I: 
       
         
           
           
               
               
           
         
       
       wherein each of Ar 1  and Ar 2  is independently chosen from an optionally substituted aromatic group. 
     
     
         23 . The method of  claim 22 , wherein said substrate further comprises at least one electrode or charge transfer layer comprising transparent collecting electrodes. 
     
     
         24 . The method of  claim 23 , wherein said squaraine compound is deposited by one or more processes chosen from vacuum deposition and solution processing. 
     
     
         25 . The method of  claim 24 , wherein said solution processing comprises one or more techniques chosen from spin coating, spray coating, dip coating, or doctor's blading. 
     
     
         26 . The method of  claim 24 , wherein said squaraine compound is sublimed during vacuum deposition one or more times. 
     
     
         27 . The method of  claim 22 , wherein the squaraine compound of formula I is deposited at a rate ranging from 0.1 to 1.5 Å/sec. 
     
     
         28 . The method of  claim 22 , wherein the deposited squaraine compound of formula I has a thickness of 100 Å or less. 
     
     
         29 . The method of  claim 22 , further comprising depositing C 60  on said squaraine compound by vacuum deposition or vapor deposition. 
     
     
         30 . The method of  claim 29 , wherein the Donor-Acceptor heterojunction is a mixed or bulk heterojunction. 
     
     
         31 . The method of  claim 29 , wherein at least at one point, said C 60  has direct contact with said substrate. 
     
     
         32 . The method of  claim 31 , wherein the C 60  is deposited at a rate of from 2 to 6 Å/s. 
     
     
         33 . The method of  claim 22 , further comprising depositing at least one layer of CuPc or NPD on the substrate prior to depositing said squaraine compound. 
     
     
         34 . The method of  claim 33 , wherein said CuPc and squaraine are deposited together to form a layer comprising a mixture of a squaraine and CuPc. 
     
     
         35 . The method of  claim 22 , wherein depositing the squaraine compound forms a discontinuous layer. 
     
     
         36 . The method of  claim 22 , said method comprising depositing two or more different squaraine films to form said Donor-Acceptor heterojunction. 
     
     
         37 . An organic photosensitive optoelectronic device comprising at least one Donor-Acceptor heterojunction formed from a mixture of at least two different squaraines, said squaraines comprising a compound of formula I: 
       
         
           
           
               
               
           
         
       
       wherein each of Ar 1  and Ar 2  is independently chosen from an optionally substituted aromatic group. 
     
     
         38 . The organic photosensitive optoelectronic device of  claim 37 , wherein the mixture of at least two different squaraines comprises at least one squaraine chosen from 2,4-Bis [4-(N,N-dipropylamino)-2,6-dihydroxyphenyl; 2,4-Di-3-guaiazulenyl-1,3-dihydroxycyclobutenediylium dihydroxide; 2,4-Bis[4-(N,N-diisobutylamino)-2,6-dihydroxyphenyl; and salts thereof.