Group IV nanoparticles in an oxide matrix and devices made therefrom
Photoactive materials made from Group IV semiconductor nanoparticles dispersed in an inorganic oxide matrix and methods for making the photoactive materials are provided. In some instances, the nanoparticles are functionalized with organosilanes to provide nanoparticle-organosilane compounds. The photoactive materials may be formed by subjecting the nanoparticles or nanoparticle compounds to a sol-gel process. The photoactive materials are well-suited for use in devices which convert electromagnetic radiation into electrical energy, including photovoltaic devices, photoconductors, and photodetectors.
1. A nanoparticle-organosilane compound comprising a Group IV nanoparticle having a surface functionalized with organosilane molecules, wherein the nanoparticle-organosilane compound has the structure (NP)—(CH 2 ) m —SiR n (OH) 3−n , or (NP)—(CH 2 )═CH—(CH 2 ) p —SiR n (OH) 3−n , wherein (NP) represents the nanoparticle, m≧2, R is an organic aliphatic or aromatic group that is unreactive toward the nanoparticles, n is ≧0, and p≧1.
2. The compound of claim 1 , wherein the compound is the product of reactions between terminal alkynyl groups of alkynyl silanes and the Group IV nanoparticle, or reactions between terminal alkenyl groups of alkenyl silanes and the Group IV nanoparticle.
3. The compound of claim 2 , wherein the organosilane molecules are selected from the group consisting of: H 2 C═CH—(CH 2 ) m —SiR n (OR′) 3−n ; and HC≡C—(CH 2 ) m —SiR n (OR′) 3-n molecules, wherein m≧1, R and R′ are organic aliphatic or aromatic groups that are unreactive toward the nanoparticles, OR′ is a functional group capable of undergoing hydrolysis, and n is ≦2.
4. The compound of claim 3 , wherein m≧2, n=1 and R and R′ are either C k H k+1 , where k≧1, or
wherein X is an atom or functional group that is unreactive toward the nanoparticle.
5. The compound of claim 1 , wherein n=0.
6. A photoactive material comprising a plurality of the nanoparticle-organosilane compounds of claim 1 in an oxide matrix.
7. The photoactive material of claim 6 , wherein the oxide matrix comprises an oxide selected from the group consisting of titanium oxides, zinc oxides, niobium oxides, tantalum oxides, tungsten oxides, molybdenum oxides, and mixtures thereof.
8. The photoactive material of claim 6 , wherein the oxide matrix is formed by a sol-gel process.
9. A photoactive device comprising a first electrode, a second electrode, and the photoactive material of any of claim 6 , wherein the photoactive material is in electrical communication with the first and second electrodes.
10. The photoactive device of claim 9 , wherein the photoactive device is a photovoltaic cell.