The latest advances in solar cell technology based on crystalline Silicon are being driven by a desire to reduce the thickness of the Silicon wafer, primarily due to the cost of Silicon. This has forced the development of new designs in three key areas; moving the front-side contact to the back to eliminate its masking effect, replacing the screen printing process used to define metal contacts, and developing methods to localize the regions of high doping to facilitate contact formation.
Emitter Wrap-Through, or EWT, is a technique being developed which utilizes an array of narrow via holes drilled across the wafer to route the front-side contact to the back. For a standard wafer, this would require the drilling of 10,000 holes within the industry-standard TAKT time of one second. The type of lasers typically used for this application have 60-100W of power, and achieve less than 4,000 holes per second. To date, ESI has demonstrated 6,200 holes per second using only 20W of PyroFlex™ laser power in a project conducted in collaboration with Fraunhofer CLT in Plymouth, MI.
Emitter Wrap-Through (EWT)
- Through-hole drilling in Silicon
- 6,200 holes/sec @ 20W
- Shaped pulses 100’s of ns
- Work done by Fraunhofer Institute CLT, Plymouth MI
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