Organic photovoltaic cell incorporating electron conducting exciton blocking layers
View Patent ↗The present disclosure relates to photosensitive optoelectronic devices including a compound blocking layer located between an acceptor material and a cathode, the compound blocking layer including: at least one electron conducting material, and at least one wide-gap electron conducting exciton blocking layer. For example, 3,4,9,10 perylenetetracarboxylic bisbenzimidazole (PTCBI) and 1,4,5,8-napthalene-tetracarboxylic-dianhydride (NTCDA) function as electron conducting and exciton blocking layers when interposed between the acceptor layer and cathode. Both materials serve as efficient electron conductors, leading to a fill factor as high as 0.70. By using an NTCDA/PTCBI compound blocking layer structure increased power conversion efficiency is achieved, compared to an analogous device using a conventional blocking layers shown to conduct electrons via damage-induced midgap states.
1. An organic photosensitive optoelectronic device comprising: two electrodes comprising an anode and a cathode in superposed relation;
a photo-active region between the two electrodes; and a blocking region located between the photo-active region and the cathode that conducts electrons and blocks excitons, wherein said blocking region comprises at least one wide-gap electron conducting exciton blocking material and at least one electron conducting material.
2. The device of claim 1 , wherein the photo-active region comprises at least one donor material and at least one acceptor material.
3. The device of claim 2 , wherein the at least one acceptor has a lowest unoccupied molecular orbital energy (LUMO-1) and the at least one electron conducting exciton blocking material has a lowest unoccupied molecular orbital energy (LUMO-2), wherein LUMO-1 and LUMO-2 are aligned to permit electron transport directly from the acceptor material to the cathode.
4. The device of claim 3 , wherein the energy gap between the first lowest unoccupied molecular orbital energy and the second lowest unoccupied molecular orbital energy is no greater than 0.3 eV.
5. The device of claim 2 , wherein the at least one donor material comprises squarine (SQ), boron subphthalocyanonine chloride (SubPc), copper phthalocyanine (CuPc), chloro-aluminum phthalocyanine (ClAlPc), poly(3-hexylthiophene) (P3HT), tin phthalocyanine (SnPc), pentacene, tetracene, diindenoperylene (DIP), and combinations thereof.
6. The device of claim 2 , wherein the at least one acceptor material is C 60 , C 70 fullerenes, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), perfluorinated copper phthalocyanine (F 16 —CuPc), PCBM, PC 70 BM, and combinations thereof.
7. The device of claim 1 , wherein the at least one electron conducting material comprises 3,4,9,10 perylenetetracarboxylic bisbenzimidazole (PTCBI).
8. The device of claim 1 , wherein the at least one wide-gap electron conducting exciton blocking material comprises 1,4,5,8-napthalene-tetracarboxylic-dianhydride (NTCDA).
9. The device of claim 1 , wherein the blocking region has a thickness ranging from 10-100 nm.
10. The device of claim 1 , wherein the at least one electron conducting material has a thickness ranging from 2-10 nm.
11. The device of claim 1 , wherein the at least one wide-gap electron conducting exciton blocking material has a thickness ranging from 5-100 nm.
12. The device of claim 1 , wherein the at least one electron conducting material comprises 3,4,9,10 perylenetetracarboxylic bisbenzimidazole (PTCBI), and the at least one wide-gap electron conducting exciton blocking material comprises 1,4,5,8-napthalene-tetracarboxylic-dianhydride (NTCDA).
13. The device of claim 12 , wherein the at least one wide-gap electron conducting exciton blocking material has a thickness ranging from 5-100 nm and the at least one electron conducting material has a thickness of up to 5 nm.
14. The device of claim 1 , wherein the device is an organic photodetector.
15. The device of claim 14 , wherein the organic photodetector is an organic solar cell exhibiting at least one of the following properties: a fill factor greater than 0.62, a spectrally corrected power conversion efficiency of at least 5.0% under 1 sun, AM1.5G illumination, or a short circuit current of at least 7.5 mA/cm 2 .
16. The device of claim 1 , wherein at least one electrode comprises transparent conducting oxides, thin metal layers, or transparent conducting polymers.
17. The device of claim 16 , wherein the conducting oxides are chosen from indium tin oxide (ITO), tin oxide (TO), gallium indium tin oxide (GITO), zinc oxide (ZO), and zinc indium tin oxide (ZITO), thin metal layers are comprised of Ag, Al, Au or combinations thereof, and the transparent conductive polymers comprise polyanaline (PANI) and 3,4-polyethylenedioxythiophene:polystyrenesulfonate (PEDOT:PSS).
18. The device of claim 1 , wherein at least one electrode comprises a metal substitute, a non-metallic material or a metallic material chosen from Ag, Au, Ti, Sn, and Al.
19. A method of making an organic photosensitive optoelectronic device, said method comprising depositing onto a substrate: two electrodes comprising an anode and a cathode in superposed relation; a photo-active region between the two electrodes; and a blocking region located between the photo-active region and the cathode that conducts electrons and blocks excitons, wherein said blocking region comprises at least one wide-gap electron conducting exciton blocking material and at least one electron conducting material.
20. The method of claim 19 , wherein the photo-active region comprises at least one donor material and at least one acceptor material.
21. The method of claim 20 , wherein the at least one donor material is chosen from squarine (SQ), boron subphthalocyanonine chloride (SubPc), copper phthalocyanine (CuPc), chloro-aluminum phthalocyanine (ClAlPc), poly(3-hexylthiophene) (P3HT), tin phthalocyanine (SnPc), pentacene, tetracene, diindenoperylene (DIP), and combinations thereof.
22. The method of claim 20 , wherein the at least one acceptor material is chosen from C 60 , C 70 fullerenes, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), perfluorinated copper phthalocyanine (F 16 —CuPc), PCBM, PC 70 BM, and combinations thereof.
23. The method of claim 19 , wherein said at least one acceptor has a lowest unoccupied molecular orbital energy (LUMO-1) and the at least one electron conducting exciton blocking material has a lowest unoccupied molecular orbital energy (LUMO-2), wherein LUMO-1 and LUMO-2 are aligned to permit electron transport directly from the photo-active region to the cathode.
24. The method of claim 23 , wherein the energy gap between the first lowest unoccupied molecular orbital energy and the second lowest unoccupied molecular orbital energy is no greater than 0.3 eV.
25. The method of claim 19 , wherein the at least one wide-gap electron conducting exciton blocking material comprises 1,4,5,8-napthalene-tetracarboxylic-dianhydride (NTCDA).
26. The method of claim 19 , wherein the blocking region has a thickness ranging from 10-100 nm.
27. The method of claim 19 , wherein the at least one electron conducting material has a thickness ranging from 2-10 nm.
28. The method of claim 19 , wherein the at least one wide-gap electron conducting exciton blocking material has a thickness ranging from 5-100 nm.
29. The method of claim 19 , wherein the at least one electron conducting material comprises 3,4,9,10 perylenetetracarboxylic bisbenzimidazole (PTCBI), and the at least one wide-gap electron conducting exciton blocking material comprises 1,4,5,8-napthalene-tetracarboxylic-dianhydride (NTCDA).
30. The method of claim 29 , wherein the at least one wide-gap electron conducting exciton blocking material has a thickness ranging from 5-100 nm and the at least one electron conducting material has a thickness of up to 5 nm.
31. The method of claim 19 , wherein at least one electrode comprises transparent conducting oxides, thin metal layers, or transparent conducting polymers.
32. The method of claim 31 , wherein the conducting oxides are chosen from indium tin oxide (ITO), tin oxide (TO), gallium indium tin oxide (GITO), zinc oxide (ZO), and zinc indium tin oxide (ZITO), thin metal layers are comprised of Ag, Al, Au or combinations thereof, and the transparent conductive polymers comprise polyanaline (PANI), and 3,4-polyethylenedioxythiophene:polystyrenesulfonate (PEDOT:PSS).
33. The method of claim 19 , wherein at least one electrode comprises a metal substitute, a non-metallic material or a metallic material chosen from Ag, Au, Ti, Sn, and Al.