Molecular compositions, materials, and methods for efficient multiple exciton generation
Embodiments of the present invention provides compounds, compositions, and methods for their preparation that provide efficient intramolecular fission, such that local order and strong nearest neighbor coupling is no longer a design constraint. Inventive materials include organic oligomers and polymers designed to exhibit strong intrachain donor-acceptor interactions and provide intramolecular singlet fission, whereby triplet populations can be generated in very high yields of, e.g., 170% or more. The inventive disclosure is directed to polymers of the general formula: [SA-SD]n with a strong electron acceptor (SA), a strong electron donor (SD), and n a positive integer equal to or greater than two; methods for their preparation and monomers used therein, blends, mixtures and formulations containing them; the use of the polymers, blends, mixtures and formulations as semiconductors in organic electronic (OE) devices, especially in organic photovoltaic (OPV) devices, and to OE and OPV devices comprising these polymers, blends, mixtures or formulations.
1. A polymer, comprising:
alternating electron donating subunits and electron accepting subunits having the formula [SD-SA]n, wherein SD is a strong electron donating subunit, SA is a strong electron accepting subunit, and n is an integer,
wherein the strong electron accepting subunit has one of the following formulas:
wherein in each of the above formulas, R 1 , R 2 , R 3 , and R 4 are selected from the group consisting of hydrogen, straight chain or branched alkyl of C 1-20 , alkenyl, alkynyl, alkoxy, halogen, sulfur, organotin compounds of the formula Sn(R 5 ) 3 ,
wherein R 5 is selected from the group consisting of C 1-10 alkyl, an oligoethylene glycol, a hydroxide, sulfate, or carbonate of a Group 2 element, C 1 -C 6 hydroxyalkyl, C 1-6 alkylcarboxylic acids, C 1-6 alkylketones, C 1-6 alkyl amines, C 1-6 alkylamides, C 1-6 carboxylate ions, and C 1-6 alkylammonium ions,
wherein, in the final polymer, at least two of R 1 to R 4 are covalent linkages to a strong electron donating subunit, and
wherein the strong electron donating subunit has at least one of:
(a) a general structural formula I or a general structural formula II,
wherein the general structural formula I is as follows:
wherein the general structural formula II is as follows:
wherein in each of the general structural formula I and the general structural formula II, each R 1 and R 2 is same or different from one another and selected from the group consisting of hydrogen, straight or branched chain C 1-20 alkyl, C 2-20 alkenyl, C 2-20 alkynyl, oligoethylene glycols, thiophene, benzene, and furan, and each of the R 3 and R 4 groups is same or different from one another and selected from the group consisting of hydrogen, straight or branched chain C 1-20 alkyl, C 2-20 alkenyl, C 2-20 alkynyl, C 1-20 alkoxy, boronic acids, boronic esters, and Sn(R 5 ) 3 , and wherein R 5 is selected from the group consisting of C 1-10 alkyl,
(b) a general structural formula III which is as follows:
wherein in the general structural formula III, “R” is the same as defined for R 1 and R 2 in accordance with general structure II above and SnR 3 is an organo-tin compound, wherein R 3 represents three (3) “R” substituents selected from the group consisting of C 1-10 alkyl, an oligoethylene glycol, a beryllium, magnesium, calcium, strontium or barium hydroxide, sulfate, or carbonate, a C 1-6 alcohol, a C 1-6 carboxylic acid, a C 1-6 ketone, a C 1-6 amines, a C 1-6 amide, a C 1-6 carboxylate ion, and a C 1-6 ammonium ion, or
(c) a general structural formula IV which is as follows:
wherein in the general structural formula IV, “R” is the same as defined for R 1 and R 2 in accordance with the general structure I and SnR 3 is an organotin compound, wherein R 3 represents three (3) “R” substituents selected from the group consisting of C 1-10 alkyl, an oligoethylene glycol, a beryllium, magnesium, calcium, strontium or barium hydroxide, sulfate, or carbonate, a C 1-6 alcohol, a C 1-6 carboxylic acid, a C 1-6 ketone, a C 1-6 amines, a C 1-6 amide, a C 1-6 carboxylate ion, and a C 1-6 ammonium ion, wherein, in the final polymer, the strong electron donating subunits of the structural formulas I-IV are covalently linked to strong electron accepting subunits via covalent linkages at at least one of any of the unsubstituted positions on the structural formulas I-IV or through one or more of R 1 to R 4 in the structural formulas I-IV, and wherein one or more R 1 to R 4 in the strong electron donating subunit represents hydrogen, and in the final polymer, one or more of R 1 to R 4 represents a covalent linkage to a strong electron accepting subunit.
2. A polymer according to claim 1 , further comprising at least one spacer between the electron donating subunits and the electron accepting subunit.
3. A polymer according to claim 2 , wherein the polymer has the formula [SD-SP-SA]n, wherein SP is a spacer.
4. A polymer according to claim 3 , wherein the polymer has the formula [SD-SP-SA-SP]n.
5. A polymer according to claim 3 , wherein the spacer is at least one monomer containing at least one or more pi bonds.
6. A polymer having the formula:
wherein “n” is a positive integer, “q” is a positive integer, and “R” may he the same or different and may be selected from: hydrogen, straight or branched chain alkyl of C 1-20 , alkenyl, alkynyl, oligoethylene glycols, and aromatic rings.
7. A polymer according to claim 6 , wherein n is 1.
8. A polymer according to claim 6 , wherein q is greater than or equal to 2.
9. A polymer having the formula:
wherein “m” is a positive integer, “n” is a positive integer, “p” is a positive integer, “q” is a positive integer, and “R” may be the same or different and may be selected from: hydrogen, straight or branched chain alkyl of C 1-20 , alkenyl, alkynyl, oligoethylene glycols, and aromatic rings.
10. A polymer according to claim 9 , wherein m is 1.
11. A polymer according to claim 9 , wherein n is 1.
12. A polymer according to claim 9 , wherein p is 1.
13. A polymer according to claim 9 , wherein q is greater than or equal to 2.
14. A photovoltaic device comprising a multi-functional layer comprising the polymer of claim: 1 .