Three-dimensional bicontinuous heterostructures, a method of making them, and their application in quantum dot-polymer nanocomposite photodetectors and photovoltaics
The present invention provides of a three-dimensional bicontinuous heterostructure, a method of producing same, and the application of this structure towards the realization of photodetecting and photovoltaic devices working in the visible and the near-infrared. The three-dimensional bicontinuous heterostructure includes two interpenetrating layers which are spatially continuous, they are include only protrusions or peninsulas, and no islands. The method of producing the three-dimensional bicontinuous heterostructure relies on forming an essentially planar continuous bottom layer of a first material; forming a layer of this first material on top of the bottom layer which is textured to produce protrusions for subsequent interpenetration with a second material, coating this second material onto this structure; and forming a final coating with the second material that ensures that only the second material is contacted by subsequent layer. One of the materials includes visible and/or infrared-absorbing semiconducting quantum dot nanoparticles, and one of materials is a hole conductor and the other is an electron conductor.
1. A nanocomposite layered device, comprising:
a three-dimensional bicontinuous heterostructure including at least two materials with a first material formed on a substrate so that a surface of the first material completely covers a surface of the substrate, a second material located on the first material, said first and second materials each having a structure and morphology that includes protrusions with substantially no islands, the first material and the second material each being spatially continuous, the protrusions from said first material penetrate into said second material and said protrusions from said second material penetrate into said first material to form an irregular interpenetrating interface between said first and second materials, the protrusions from the first material being opposite the surface of the first material that completely covers the surface of the substrate;
at least one of said first and second materials includes at least one of a plurality of visible-light absorbing semiconducting quantum dot nanoparticles and/or at least one of a plurality of infrared-light absorbing semiconducting quantum dot nanoparticles; and
wherein upon absorption of light by said visible and/or infrared-absorbing quantum dot nanoparticles, an electron-hole pair is formed which drifts to said interpenetrating interface wherein said the electron-hole pair is separated.
2. The nanocomposite layered device as claimed in claim 1 wherein a negative electrical bias is applied to one material and an positive electrical bias is applied to the other material for electron and hole extraction under illumination.
3. The nanocomposite layered device according to claim 2 wherein a second electrode applied to a top surface of said second material for electron extraction is selected from the group consisting of Mg, Al, and Ag.
4. The nanocomposite layered device according to claim 3 wherein the second electrode includes an interlayer of an electron-rich material.
5. The nanocomposite layered device according to claim 4 wherein the electron-rich material is Li.
6. The nanocomposite layered device as claimed in claim 1 including a first electrode contacted to said first material and a second electrode contacted to said second material, wherein the work functions of the materials are such that electrons travel towards one of said first and second electrodes, and holes travel to the other electrode, resulting in a photovoltaic effect, characterized by a development of a sustained potential difference accompanied by net current flow into an external circuit without the application of an external bias to said first and second electrodes.
7. The nanocomposite layered device as claimed in claim 6 wherein the first electrode comprises a hole conducting material.
8. The nanocomposite layered device according to claim 1 wherein said first material includes the visible and/or infrared-absorbing semiconducting quantum dot nanoparticles alone, and wherein the second material is selected from the group consisting of semiconductor polymers, organic molecules which transport electrons, holes or both, metals, pseudo-metallic materials, conducting oxides, Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)(PEDOT:PSS) and combinations thereof.
9. The nanocomposite layered device according to claim 8 wherein said materials comprised of visible and/or infrared-absorbing semiconducting quantum dot nanoparticles alone are formed of nanoparticles which have had organic ligands removed from the surfaces thereof.
10. The nanocomposite layered device according to claim 8 wherein the conductive oxide is selected from the group consisting of indium tin oxide, tin oxide, antimony-doped indium tin oxide and antimony-doped tin oxide.
11. The nanocomposite layered device according to claim 8 wherein the organic molecules are selected from the group consisting of oligomeric and polymeric organic molecules.
12. The nanocomposite layered device according to claim 11 wherein the polymeric organic molecules are selected from the group consisting of poly[2-rnethoxy -5-(2′-ethylhexyloxy-p-phenylenevinylene)](MEH-PPV), polythiophene including regio-regular polythiophene.
13. The nanocomposite layered device according to claim 1 wherein said second material includes one or more of semiconducting quantum dot nanoparticles selected from a group consisting of visible-absorbing semiconducting quantum dot nanoparticles and infrared-absorbing semiconducting quantum dot nanoparticles.
14. The nanocomposite layered device according to claim 1 wherein said first material includes first visible and/or infrared-absorbing semiconducting quantum dot nanoparticles alone, and wherein said second material includes second visible and/or infrared-absorbing semiconducting quantum dot nanoparticles different from said first visible and/or infrared-absorbing semiconducting quantum dot nanoparticles alone.
15. The nanocomposite layered device according to claim 14 wherein said visible and/or infrared-absorbing semiconducting quantum dot nanoparticles in said first and second materials are made of different semiconductor materials which absorb at different wavelengths.
16. The nanocomposite layered device according to claim 14 wherein said visible and/or infrared-absorbing semiconducting quantum dot nanoparticles in said first and second materials are made of the same semiconductor material but have different sizes which absorb at different wavelengths.
17. The nanocomposite layered device according to claim 1 wherein said second material is a composite material containing a first semiconducting polymer in combination with said visible and/or infrared-absorbing semiconducting quantum dot nanoparticles, and wherein the first material is selected from the group consisting of semiconductor polymers, organic molecules which transport electrons, holes or both, metals, pseudo-metallic materials, conducting oxide and PEDOT:PSS and combinations thereof.
18. The nanocomposite layered device according to claim 17 wherein the composite material comprises a material having a ratio of quantum dot particles to semiconducting polymer that is greater than about 80% by mass.
19. The nanocomposite layered device according to claim 18 wherein the ratio is about 90% by mass.
20. The nanocomposite layered device according to claim 1 wherein the substrate is a transparent substrate selected from a group consisting of quartz, glass and a transparent polymer.
21. The nanocomposite layered device according to claim 1 wherein the visible and/or infrared-absorbing semiconducting quantum dot nanoparticles are selected from the group consisting of Ge, Si, SiGe, PbS, CdS, CdSe, PbSe, InAs, InP, InSb, InGaAsP, core-shell nanoparticles consisting of combinations of semiconductors arrayed in a core-shell geometry.
22. The nanocomposite layered device according to claim 1 wherein the visible and/or infrared-absorbing semiconducting quantum dot nanoparticles are initially coated with organic ligands selected from the group consisting of amines, thiols, fatty acids, phosphines and phosphine oxides.
23. The nanocomposite layered device according to claim 1 wherein said protrusions from said first material penetrate into said second material and said protrusions from said second material penetrate into said first material have lengths in a range from about 200 nm to about 2 microns, and wherein a portion of the first material formed on said substrate outside of said interpenetrating interface has a thickness in a range from about 2 to about 200 nm, and wherein a portion of the second material outside of said interpenetrating interface has a thickness in a range from about 2 to about 200 nm.
24. The nanocomposite layered device according to claim 1 wherein said visible and/or infrared-absorbing semiconducting quantum dot nanoparticles absorb light in a wavelength region from about 800 nm to about 2000 nm.
25. The nanocomposite layered device according to claim 1 wherein said substrate is glass, said first material includes indium tin oxide (ITO) coated with poly (p-phenylenevinylene) (PPV), and wherein said second material includes and mixture of MEH-PPV and PbS nanocrystals.
26. The nanocomposite layered device according to claim 1 wherein said substrate is a transparent substrate, said first material is a semiconducting polymer layer coating said substrate, and wherein said second material is a layer formed of infrared-absorbing quantum dot nanoparticles.
27. The nanocomposite layered device according to claim 1 wherein said second material is selected from the group consisting of semiconductor polymers, organic molecules which transport electrons, holes or both, metals, pseudo-metallic materials, conducting oxide and (PEDOT:PSS) and combinations thereof.