Organic monolayer passivation and silicon heterojunction photovoltaic devices using the same
A method for inorganic surface passivation in a photovoltaic device includes etching a native oxide over an inorganic substrate, the inorganic substrate having a surface; and forming an organic monolayer on the surface of the inorganic substrate to form a heterojunction, the organic monolayer having the following formula: ˜X—Y, wherein X is an oxygen or a sulfur; Y is an alkyl chain, an alkenyl chain, or an alkynyl chain; and X covalently bonds to the surface of the inorganic substrate by a covalent bond.
1. A heterojunction in a photovoltaic device, comprising;
an inorganic substrate having a surface;
an organic monolayer on the surface of the inorganic substrate, the organic monolayer having the following formula:
˜X—(CH 2 ) n -CH 3 ,
wherein X is an oxygen or a sulfur; n is an integer from about 4 to about 21; and X covalently bonds to the surface of the inorganic substrate to form a covalently bonded ether or a covalently bonded thioether on the surface;
an organic semiconductor material on a surface of the organic monolayer, the organic semiconductor material being substantially free of doping; and
a conductive electrode disposed onto at least on a portion of the organic semiconductor material.
2. The heterojunction of claim 1 , wherein the inorganic substrate comprises an n-type semiconductor, and the organic semiconductor has electron blocking properties, hole transport properties, or a combination thereof.
3. The heterojunction of claim 1 , wherein the inorganic substrate comprises an n-type semiconductor, and the conductive electrode comprises a high work-function material.
4. The heterojunction of claim 1 , wherein the organic monolayer has a thickness in a range from about 2 to about 3 nm.
5. The heterojunction of claim 1 , wherein the inorganic substrate comprises a p-type semiconductor, and the organic semiconductor has hole blocking properties, electron transport properties, or a combination thereof.
6. The heterojunction of claim 1 , wherein the inorganic substrate comprises a p-type semiconductor, and the conductive electrode comprises of a low work-function material.
7. The heterojunction of claim 1 , wherein the inorganic substrate comprises silicon.
8. The heterojunction of claim 1 , wherein the organic semiconductor has a thickness in a range from about 3 to about 25 nm.
9. The heterojunction of claim 1 , wherein the inorganic substrate is a silicon wafer.
10. The heterojunction of claim 1 , wherein the organic monolayer has a thickness of about 0.5 to about 5 nm.
11. The heterojunction of claim 1 , wherein the organic monolayer is substantially free of impurities.