Higher selectivity, method for passivating short circuit current paths in semiconductor devices
AssigneeUnited Solar Ovonic LLC
InventorsJonathan Call, Greg DeMaggio, Ginger Pietka
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Abstract
Certain modifications and additions to the prior art short passivation technique have lead to improvements in the low light voltage of solar cells which are made using the improved passivation technique. Examples of the modifications include: 1) reducing the voltage bias on the cell while increasing the time of application of the voltage; 2) reversing the polarity of the voltage bias on the devices; 3) alternating pulsing between forward and reverse polarity bias; or 4) applying light energy simultaneously with an electrical bias voltage.
Claims21
A method of passivating short circuit defects in a thin film large area photovoltaic module comprising a substrate electrode, an intermediate body including a plurality of continuous layers disposed atop said substrate and selected from the group consisting of dielectrics, semiconductors, and combinations thereof, and a top electrode disposed atop said intermediate body, said method comprising the steps of:
- providing a solution of a passivation agent in contact with at least those portions of said electrode proximate said defects;
- and
- disposing a counter-electrode in electrical communication with said solution of said passivation agent;
- providing a power supply in electrical communication with both said counter-electrode and said substrate electrode of said photovoltaic module for applying a potential between said substrate electrode and said counter-electrode;
- applying electrical energy to said electrodes and optionally light energy to said photovoltaic device thereby activating said passivation agent proximate said defects so as to facilitate modification of the electrode material, whereby said defects regions are substantially electrically isolated from the remainder of said electrode material;
- and
- controlling the voltage and duration of the application of said electrical energy and, if applied, the intensity and duration of said light energy so as to ensure high selectivity of modification of the electrode material adjacent said defect, while leaving the electrode material adjacent non-defect areas in its unmodified form.
A method of passivating short circuit defects in a thin film large area photovoltaic module comprising a substrate electrode, an intermediate body including a plurality of continuous layers disposed atop said substrate and selected from the group consisting of dielectrics, semiconductors, and combinations thereof, and a top electrode disposed atop said intermediate body, said method comprising the steps of:
- providing a solution of a passivation agent in contact with at least those portions of said electrode proximate said defects;
- and
- disposing a counter-electrode in electrical communication with said solution of said passivation agent;
- providing a power supply in electrical communication with both said counter-electrode and said substrate electrode of said photovoltaic module for applying a potential between said substrate electrode and said counter-electrode;
- applying electrical energy to said electrodes thereby activating said passivation agent proximate said defects so as to facilitate modification of the electrode material, whereby said defects regions are substantially electrically isolated from the remainder of said electrode material;
- and
- controlling the voltage and duration of the application of said electrical energy so as to ensure high selectivity of modification of the electrode material adjacent said defects, while leaving the electrode material adjacent non-defect areas substantially unmodified, wherein said voltage induces current within the device such that the ratio of the current flowing through said defects to the current flowing through the non-defect portions of the device is at least 4:1.
Dependencies are inferred from the claim text.