Material Independent Rear pAssivating Contact soLar cEll
Many companies expect that after the step from aluminum back surface field (Al BSF) towards p-type passivating emitter and rear contact (p-PERC), the next silicon PV technology will be n-PERT, because of its enhanced bifaciality of >95% and higher efficiency potential. However, large penetration of n-type cell technologies so far has been hampered by higher wafer prices, more complex manufacturing, high silver consumption and the fact that it is a revolutionary rather than evolutionary approach compared to p-type cell production.
To accommodate the demands from the PV industry for high, stable efficiencies and high energy yield, and at the same time offer compatibility for the majority of existing manufacturing technology, we will research and develop a bifacial Material Independent Rear pAssivated Contact soLar cEll. The “Miracle” concept, with a target efficiency of 23%, is based on a p+ polysilicion passivating contact at the rear and is applicable to both p-type and n-type Si cells. It only requires a simple and cost-effective upgrade to the present p-type cell production toolset, based on new equipment from Tempress Systems BV.
The project partners bring in complementary expertises that are all crucial for the development of the Miracle concept.
Tempress will develop their equipment and processes for high quality p+ polysilicon (poly-Si). Furthermore, Tempress will focus on n+ POCl3 diffusion and a combination of annealing of the polysilicon layer and diffusion of the front side phosphorus will be studied.
The UT will explore the processes and limitations for contacting the polysilicon layers using high quality metallization techniques from the IC industry. The TU/e will work on tunnel oxides for poly-Si passivating contacts and will also explore higher performance (lower light absorption, better passivation) using metal oxide based transparent passivating electron contacts for the front side. The laboratory technologies that will be investigated by the universities will show the full potential and crucial points of improvements for the p+ poly passivating layers in the Miracle cell.
ECN will design and model the Miracle concept, and integrate the developed processes on next generation p-type and n-type cells.
Pilot production together with potential customers will be targeted by Tempress.
The project will deliver the architecture and processes for the Miracle cell. The target cell efficiency of 23% is 1-2% abs. higher than current stabilized p-PERC efficiency. The bifaciality will add 10 - 25% to the module’s energy yield. Because Miracle is applicable to both p- and n-type wafers, it will also enable an easy shift from p- to n-type material for cell manufacturers that adopt this technology.
The project result will be a unique product based on Dutch equipment and technology, that will be largely compatible for implementation in nearly all current and future cell lines in the world.