Method for manufacturing CIS-based thin film solar cell
In order to manufacture a CIS-based thin film solar cell that can achieve high photoelectric conversion efficiency by adding an alkali element to a light absorbing layer easily and with good controllability, a backside electrode layer ( 2 ) is formed on a substrate ( 1 ). Then, a p-type CIS-based light absorbing layer ( 3 ) is formed on backside electrode layer ( 2 ), and then an n-type transparent and electroconductive film ( 5 ) is formed on this p-type CIS-based light absorbing layer ( 3 ). At this time, the backside electrode layer ( 2 ) is constituted by forming a first electrode layer ( 21 ) using a backside electrode material in which an alkali metal is mixed and, then forming a second electrode layer ( 22 ) using the backside electrode material that does not substantially contain the alkali metal.
1. A method for manufacturing a CIS-based thin film solar cell comprising:
forming a backside electrode layer on a substrate;
forming a p-type CIS-based light absorbing layer on said backside electrode layer; and
forming an n-type transparent and electroconductive film on said p-type CIS-based light absorbing layer,
wherein said forming of said backside electrode layer comprises forming a first electrode layer using a first target or a first evaporation source that comprises a backside electrode material and an alkali metal and forming a second electrode layer using a second target or a second evaporation source that comprises said backside electrode material but does not substantially contain an alkali metal.
2. A method for manufacturing a CIS-based thin film solar cell according to claim 1 , wherein said substrate is formed of any of high strain point glass, non-alkali glass, metal and resin.
3. A method for manufacturing a CIS-based thin film solar cell according to claim 2 , wherein said backside electrode material is Mo and said alkali metal is Na.
4. A method for manufacturing a CIS-based thin film solar cell according to claim 3 , wherein said first electrode layer is formed using Mo containing at least 0.3 at % of Na as a target or an evaporation source.
5. A method for manufacturing a CIS-based thin film solar cell according to claim 3 , wherein said second electrode layer is formed using Mo containing 0.01 at.% or less of Na as a target or an evaporation source.
6. A method for manufacturing a CIS-based thin film solar cell according to claim 4 , wherein said second electrode layer is formed using Mo containing 0.01 at. % or less of Na as a target or an evaporation source.
7. A method for manufacturing a CIS-based thin film solar cell according to claim 1 , wherein said first electrode layer and said second electrode layer are formed by any of sputtering, evaporation and ion plating.
8. A method for manufacturing a CIS-based thin film solar cell according to claim 1 , wherein said backside electrode material is any of Mo, Ti and Cr.
9. A method for manufacturing a CIS-based thin film solar cell according to claim 1 , wherein said alkali metal is any of Na, K and Li.
10. A method for manufacturing a CIS-based thin film solar cell according to claim 1 , wherein said p-type light absorbing layer is formed by selenization/sulfurization or multi-source coevaporation.
11. A method for manufacturing a CIS-based thin film solar cell according to claim 1 , further comprising forming an n-type high resistance buffer layer between said forming said p-type light absorbing layer and said forming said n-type transparent and electroconductive film.