OBJECTIVES OF THE PROJECT
Higher efficiency and lower production cost are essential to bring the Cost/Wp of industrial PV modules down to acceptable levels. To achieve the first criteria, selective emitter approaches have been successful in laboratory level but remain unacceptable for implementation in industry due to an increased number of steps, heavy usage of chemicals, higher thermal budget & production cost. In this project, optical thermal processing based on Rapid Thermal Processing (RTP) technology will be applied in order to fabricate industrial high efficiency selective emitter solar cells in single thermal step by engineered selective light and printing technologies involving neither photolithographic steps nor prolonged thermal treatments. This low thermal budget scheme will provide a cost-effective and faster process to manufacture industrial selective emitter cells with high efficiencies
Rapid Thermal Processing (RTP) using radiation from tungsten-halogen lamps as heat source has been seen for nearly 15 years as a very promising candidate to replace conventional furnace annealing. Research on various aspects of RTP in solar cells has given very promising outcome in the EC Contract "LowThermCells". The optical transfer of energy in RTP can be used to go further forward in promising ways to fabricate industrial selective emitter cells.
- Selective emitter formation by spectrally engineered lamp heating and by groove engineering that results in differential diffusion of dopants thereby forming selective emitter in single step in very short time. - use of selectively printed/deposited doping sources for fast lamp annealing in belt or RTP furnaces equipped with lamps
- application of an efficient surface passivation scheme that is very necessary for high efficiency selective emitter cells. (rapid thermal oxidation and/or low temperature surface passivation with high through-put compatibility)
- screenprinting metallization for selective emitters with high through-put pilotline equipment and fast-firing of metal contacts in lamp furnaces
The main expected achievements of the Light-Print-Cells (LPC) project, include the:
- Development of high through-put & high efficiency low thermal budget process scheme acceptable to industry to fabricate single-step selective emitter cells.
- Enhancement of the through-put of lamp furnaces for the new generation of solar cells.
- Reduction of chemical steps, making the process environmentally safer. Performance target: 15-15.5% on multi- and 17-17.5% efficient encapsulated CzSi; 100 cm2 cells. These values represent 2% - 3% absolute percentage improvement in efficiency over today's industrial screenprinted cells. The simplicity and industrial compatibility of the present proposal will bring down the cost to < 1 XEU/Wp.
Funding SchemeCSC - Cost-sharing contracts
00060 Roma - Santa Maria Di Galeria
79110 Freiburg (In Breisgau)
38300 Bourgoin Jallieu