Compound thin-film solar cell and process for producing the same

Abstract

A method of fabricating a thin-film compound solar cell having an n-type buffer layer formed therein for providing a heterojunction with a p-type compound semiconductor light absorbing layer formed on a back electrode by applying a chemical bath deposition (CBD) process using an aqueous solution for dipping the light absorbing layer to deposit particles on the surface thereof. In this process, the temperature of the solution is controlled from low to high to increase sizes of the particles to be deposited on the light absorbing layer so as to form the buffer layer which possesses a high optical transmittance, tight adherence to the light absorbing layer and conformity with the transparent electrode formed thereon even if it would be made of InS material generally possessing a small bandgap and hard to pass light of short wavelengths.

What is claimed is: 
     
         1 . A thin-film compound solar cell comprising:
 a p-type light absorbing layer; and   an n-type buffer layer which is in heterojunction with the light absorbing layer;
 wherein the buffer layer includes InOH.InO; 
 wherein the buffer layer includes a first side at a side of the absorbing layer and a second side in an opposite side of the first side; 
 wherein the first side comprises more InS than the second side does; 
 wherein the second side comprises more InOH.InO than the first side does; and 
 wherein the buffer layer is formed of deposits of InS particles and InOH.InO particles on the light absorbing layer, and grain sizes of particles in the second side are larger than grain sizes of particles in the first side. 
   
     
     
         2 . The thin-film compound solar cell according to  claim 1 , wherein the difference in grain sizes is caused by varying the temperature of a solution used in a chemical bath deposition process to form the buffer layer.