Although the price of solar panels has recently decreased considerably, the production cost of solar cells is still too high for the generated electricity to compete with bulk electricity prices. The Dutch STW program FLASH aims at reducing the production costs of photovoltaic (PV) modules by improving the solar cell conversion efficiency, reducing materials consumption and using abundant materials only, and by applying low-cost and low-temperature processing methods, which lowers the energy costs in manufacturing as well. We focus on silicon heterojunction (SHJ) solar cells, because they combine the high efficiency of crystalline silicon (c-Si) wafer technology with the high throughput, low-cost production technologies for amorphous silicon thin-film solar cells. Thin film technology provides excellent methods for surface passivation and junction formation at low processing temperatures. Surface passivation, a method to electronically de-activate defects at the interface, is crucial for reducing losses in SHJ solar cells and leads to very high efficiencies. At present the world record efficiency of 25.6% by Panasonic for SHJ cells is even higher and is obtained on larger area than that of wafer-based technologies using conventional diffusion processes for junction formation. SHJ devices have lower mechanical stress, which facilitates the use of thinner wafer material. This in turn facilitates a major contribution to cost reduction and improves the environmental profile of solar electricity significantly. We aim to further develop this by (i) smart defect engineering. In this approach new TCOï¿½s deposited by Atomic Layer Deposition are implemented; and (ii) the development of new silicon heterojunction cell structures and their production technology.
ECN - Solliance, Eindhoven University of Technology
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