Method To Synthesize Colloidal Iron Pyrite (FeS2) Nanocrystals And Fabricate Iron Pyrite Thin Film Solar Cells

Abstract

Systems and methods are provided for the fabrication and manufacture of efficient, low-cost p-n heterojunction pyrite solar cells. The p-n heterojunction pyrite solar cells can include a pyrite thin cell component, a window layer component, and a top surface contact component. The pyrite thin cell component can be fabricated from nanocrystal paint deposited onto metal foils or microcrystalline pyrite deposited onto foil by chemical vapor deposition. A method of synthesizing colloidal pyrite nanocrystals is provided. Methods of manufacturing the efficient, low-cost p-n heterojunction pyrite solar cells are also provided.

1 . A pyrite heterojunction thin film photovoltaic device comprising
 a conductive bottom substrate acting as an electrical contact;   a pyrite thin film;   a semiconductor window layer used to form a junction with the pyrite layer to create a photovoltaic effect;   a transparent top contact; and   an encapsulation layer encapsulating the photovoltaic.   
     
     
         2 . The device of  claim 1  wherein the substrate comprises a flexible metal foil. 
     
     
         3 . The device of  claim 1  wherein the pyrite thin film comprises colloidal pyrite nanocrystals. 
     
     
         4 . The device of  claim 1  wherein the pyrite thin film comprises chemical vapor deposited pyrite. 
     
     
         5 . The device of  claim 1  wherein the semiconductor window layer comprises zinc sulfide or cadmium sulfide. 
     
     
         6 . The device of  claim 1  wherein the transparent top contact comprises doped zinc oxide. 
     
     
         7 . The device of  claim 1  further comprising current-collecting structures. 
     
     
         8 . A method for producing pyrite thin films, comprising the steps of
 depositing a thin film of pyrite onto a substrate; and   sintering the thin film of pyrite in sulfur-containing atmospheres.   
     
     
         9 . The method of  claim 8  further comprises the step of synthesizing colloidal pyrite nanocrystals, wherein the thin film of pyrite comprising a thin film of pyrite nanocrystals. 
     
     
         10 . The method of  claim 9  wherein the step of depositing pyrite nanocrystals includes dipping, spinning, dropping, printing, or spraying onto the substrate. 
     
     
         11 . The method of  claim 8  wherein the sulfur-containing atmospheres comprises S 2 , H 2 S, H 2 , or tert-butyl disulfide. 
     
     
         12 . The method of  claim 8  wherein the substrate is flexible. 
     
     
         13 . The method of  claim 12  wherein the substrate comprises an electrically conductive metal foil that is electrically conductive. 
     
     
         14 . The method of  claim 13  wherein the metal foil serves as a bottom contact in a pyrite thin film solar cell. 
     
     
         15 . The method of  claim 9  further comprising stabilizing the thin film of pyrite nanocrystal with ligands. 
     
     
         16 . The method of  claim 15  wherein the ligands comprise one of long-chain octadecylxanthates, alkylammonium, or alkylxanthates. 
     
     
         17 . The method of  claim 9  further comprising the steps of purifying the colloidal pyrite nanocrystals. 
     
     
         18 . The method of  claim 9  wherein the step of synthesizing colloidal pyrite nanocrystals comprises the steps of
 creating a reaction solution by mixing FeCl 2  with octadecylamine; 
 degassing the reaction solution; 
 creating an injection solution by injecting and dissolving sulfur in a solvent; 
 degassing the injection solution; 
 raising the temperature of the reaction solution; 
 adding the injection solution to the reaction solution to create a reaction mixture; and 
 heating the reaction solution for a predetermined period of time. 
 
     
     
         19 . The method of  claim 18  wherein the solvent comprises one of diphenyl ether, tri-n-octylphosphine oxide, octadecene, nonpolar organic solvent, or water. 
     
     
         20 . The method of  claim 18  wherein the step of raising the temperature of the reaction solution includes raising the temperature to 220° C. 
     
     
         21 . The method of  claim 18  wherein the step of heating the reaction solution includes heating the reaction solution for 2 hours. 
     
     
         22 . The method of  claim 17  wherein the step of purifying the colloidal pyrite nanocrystals consists of washing the colloidal pyrite nanocrystals with a chloroform/ethanol mixture. 
     
     
         23 . The method of  claim 17  wherein the substrate is one of a metal foil, glass, quartz, or silicon. 
     
     
         24 . The method of  claim 17  wherein the step of depositing the colloidal pyrite nanocrystals onto a substrate comprises the steps of dipping the substrate a plurality of times into a solution of colloidal pyrite nanocrystals. 
     
     
         25 . The method of  claim 24  wherein the solution of colloidal pyrite nanocrystals includes a mixture of colloidal pyrite nanocrystals and hydrazine. 
     
     
         26 . The method of  claim 17  wherein the step of depositing the colloidal pyrite nanocrystals onto a substrate includes spraying, inkjet printing, painting, or doctor blading the colloidal pyrite nanocrystals onto the substrate. 
     
     
         27 . The method of  claim 8  wherein the step of depositing a thin film of pyrite includes depositing pyrite onto the substrate by chemical vapor deposition. 
     
     
         28 . The method of  claim 27  wherein the pyrite is microcrystalline pyrite. 
     
     
         29 . A method of synthesizing colloidal pyrite nanocrystals comprising the steps of:
 heating FeCl 2  and elemental sulfur in octadecylamine and diphenyl ether to form colloidal pyrite nanocrystals; and   forming colloidal pyrite nanocrystals.   
     
     
         30 . The method of  claim 29  wherein the step of heating includes heating the FeCl 2  and elemental sulfur in octadecylamine and diphenyl ether to 220° C. for a plurality of hours.