Formation of CIGS absorber layer materials using atomic layer deposition and high throughput surface treatment

Abstract

An absorber layer may be formed on a substrate using atomic layer deposition reactions. An absorber layer containing elements of groups IB, IIIA and VIB may be formed by placing a substrate in a treatment chamber and performing atomic layer deposition of a group IB element and/or one or more group IIIA elements from separate sources onto a substrate to form a film. A group VIA element is then incorporated into the film and annealed to form the absorber layer. The absorber layer may be greater than about 25 nm thick. The substrate may be coiled into one or more coils in such a way that adjacent turns of the coils do not touch one another. The coiled substrate may be placed in a treatment chamber where substantially an entire surface of the one or more coiled substrates may be treated by an atomic layer deposition process. One or more group IB elements and/or one or more group IIIA elements may be deposited onto the substrate in a stoichiometrically controlled ratio by atomic layer deposition using one or more self limiting reactions.

1 . A process for preparing an absorption layer of a solar cell composed of a 1B-3A-Se compound, comprising:
 (a) preparing a mixture paste of Group 1B metal selenide particles and Group 3A metal selenide particles as reactants; (b) applying the paste to a base material; and (c) subjecting the resulting coating layer to rapid thermal processing.   
     
     
         2 . The process according to  claim 1 , wherein the Group 1B metal selenide is a copper selenide (Cu—Se). 
     
     
         3 . The process according to  claim 2 , wherein the copper selenide (Cu—Se) is prepared by adding a copper salt and selenious acid (H 2 SeO 3 ) to a solvent and heating the resulting mixture. 
     
     
         4 . The process according to  claim 1 , wherein the Group 3A metal selenide is an indium selenide (In—Se) or gallium selenide (Ga—Se). 
     
     
         5 . The process according to  claim 4 , wherein the indium selenide (In—Se) is prepared by adding an indium salt and selenious acid (H 2 SeO 3 ) to a solvent and heating the resulting mixture. 
     
     
         6 . The process according to  claim 1 , wherein the metal selenide particles have a particle diameter of 5 nm to 10 μm. 
     
     
         7 . The process according to  claim 6 , wherein the metal selenide particles have a particle diameter of 50 nm to 5 μm. 
     
     
         8 . The process according to  claim 1 , wherein the mole ratio of Cu/(In+Ga) is in the range of 0.6 to 1.5 and the mole ratio of Ga/(Ga+In) is in the range of 0 to 0.5, when the copper selenide (Cu—Se) is used as the Group 1B metal selenide, and indium selenide (In—Se) and/or gallium selenide (Ga—Se) are used as the Group 3A metal selenide. 
     
     
         9 . The process according to  claim 1 , wherein the coating layer has a monolayer or multilayer structure and has a total thickness of 3 to 5 μm. 
     
     
         10 . The process according to  claim 9 , wherein the coating layer is composed of a trilayer structure, and the bottom first layer has a mole ratio of Cu/(In+Ga)=0 to 0.9 and a thickness of 0.1 to 1.0 μm, the intermediate second layer has a mole ratio of Cu/(In+Ga)=0.8 to 3.0 and a thickness of 0.5 to 3.0 μm, and the top third layer has a mole ratio of Cu/(In+Ga)=0 to 0.9 and a thickness of 0.1 to 1.0 μm. 
     
     
         11 . The process according to  claim 1 , wherein the rapid thermal processing is carried out at a temperature of 400 to 600° C. for 1 to 30 min. 
     
     
         12 . A metal selenide mixture paste comprising Group 1B metal selenide particles and Group 3A metal selenide particles. 
     
     
         13 . The paste according to  claim 12 , wherein the paste comprises indium selenide (In—Se) particles and copper selenide (Cu—Se) particles. 
     
     
         14 . The paste according to  claim 12 , wherein the solvent of the paste is one or more solvents selected from the group consisting of water, alcohol-based compounds, carbonate-based compounds and glycol-based compounds. 
     
     
         15 . The paste according to  claim 12 , wherein the paste further includes one or more dopants selected from the group consisting of Na, K, Ni, P, As, Sb and Bi. 
     
     
         16 . The paste according to  claim 12 , wherein the paste further includes a binder that assists in formation of the coating layer. 
     
     
         17 . A solar cell comprising an absorption layer which is prepared by the process of  claim 1 . 
     
     
         18 . The cell according to  claim 17 , wherein the compound of the absorption layer is Cu(In,Ga)Se 2 .