High efficiency solar cells and manufacturing methods
A Schottky contact photovoltaic energy conversion cell. The Schottky contact photovoltaic energy conversion cell comprises a flexible substrate and a first array of a plurality of closely-spaced microscale pillars connected to a first electrical cell contact. The pillars and the contact are formed of (or having a top) layer of a first Schottky metal material with a work function selected for efficiently collecting photogenerated electrons. The Schottky contact photovoltaic energy conversion cell further comprises a second array of a plurality of closely-spaced microscale pillars connected to a second electrical cell contact. The pillars and the contact are formed of (or having a top) layer of a second Schottky metal material with a work function selected for efficiently collecting photogenerated holes. The Schottky contact photovoltaic energy conversion cell further comprises a semiconductor absorber thin-film layer covering the first and second contacts and filling spaces among all the pillars, for creating photogenerated electrons and holes.
1. A method to manufacture a Schottky contact photovoltaic energy conversion cell comprising:
using a roll of a flexible substrate material moving between an input substrate feeder and an output substrate receiver through a continuous flow in-line cell factory; and
using a sequence of substrate processing tools within said in-line cell factory, said tools comprising physical-vapor deposition, metal plating, and pattern transfer equipment,
wherein said material roll goes through the sequence to form interdigitated arrays of Schottky-barrier lines and pillars covered with a semiconductor absorber layer, the sequence comprising the steps:
connecting a first array of a plurality of closely-spaced microscale pillars to a first electrical cell contact, said pillars and said contact are formed of (or having a top) layer of a first Schottky metal material with a work function selected for efficiently collecting photogenerated electrons;
connecting a second array of a plurality of closely-spaced microscale pillars to a second electrical cell contact, said pillars and said contact are formed of (or having a top) layer of a second Schottky metal material with a work function selected for efficiently collecting photogenerated holes; and
depositing a semiconductor absorber thin-film layer covering said first and second contacts and filling spaces among said pillars, for creating photogenerated electrons and holes.
2. The method of claim 1 , wherein said interdigitated arrays of Schottky-barrier lines and pillars are formed in a pattern that alternates said first array of a plurality of closely-spaced microscale pillars and said second array of a plurality of closely-spaced microscale pillars.
3. The method of claim 1 , wherein said interdigitated arrays of Schottky-barrier lines and pillars are formed in straight line patterns.
4. The method of claim 1 , wherein said interdigitated arrays of Schottky-barrier lines and pillars are formed in zigzag line patterns.
5. The method of claim 1 , wherein said first array of a plurality closely-spaced microscale pillars are symmetrically surrounded by said second array of a plurality of closely-spaced micro-pillars and vice versa.
6. The method of claim 1 , wherein said first array of a plurality of closely-spaced microscale pillars and said second array of a plurality of closely-spaced micro-pillars are spaced such that there is a large enough built-in electric field E bi that will sweep photo-generated carriers towards said first and second electrical cell contacts for collection.