Minneapolis, Minn., U.S.A. - October 27, 2009 - Despatch Industries, a leading technology and equipment provider for the solar industry, is releasing the results of a study the company conducted on enabling thin wafers to become high efficiency silicon solar cells. The results were presented in a technical paper at the EU Photovoltaic Solar Energy Conference in Hamburg, Germany.
The preface of Despatch's study was to show that the optimization of a simple, low-temperature process can successfully remove the bow from thin wafers that have been fired; and that this practice can be done without degrading electrical or mechanical performance. The study was performed using Despatch's In-line Rapid Thermal Shock (IL-RTS) tool to carry out the low-temperature de-bowing step and wafers of 180º and below.
The IL-RTS is a tool that Despatch developed specifically to address the issue of bowing in thin wafers. The IL-RTS features a simple, in-line process that applies a low-temperature thermal spike which rapidly cools wafers to below 50ºC and stabilizes thermal stresses, causing the wafer bow to diminish. Wafers are then moved into a heated zone that warms them above the dew point temperature to prevent condensation. The IL-RTS is an industry alternative to using low-bow pastes which decreases overall cell efficiency.
Results of the study concluded that low temperature thermal processing (utilizing the IL-RTS tool) reduces bowing in wafers by up to 75 percent. No electrical performance or mechanical degradation occurred following IL-RTS treatment. While re-bowing can occur over time, the overall bow reduction remained between 50 and 60 percent.
Bow removal using the IL-RTS allows solar cell manufacturers many benefits. In addition to gaining better control of their wafer bowing, manufacturers have more choices in aluminum paste selection and can extend the life of their current paste while reducing wafer thickness. Manufacturers are also better able to process cells after firing and during module assembly with less handling and breakage issues.
The complete technical paper can be found on Despatch's website: http://www.despatch.com/cleantech/literature/ .
Despatch Industries designs and engineers market-leading tools and technology for the global solar cell manufacturing industry. Despatch equipment is consistently recognized for exceptional performance and process quality, optimal cell efficiency, maximum uptime and reduced operating costs. For more information on Despatch visit our website: http://www.despatch.com