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USA: Scientists Develop New Photovoltaic Material
2019-11-26
American scientists have developed a new type of photovoltaic material, and solar panels made from it are low-cost and highly efficient. For more than 40 years, scientists have hoped to develop bulk photovoltaic materials that can utilize not only ultraviolet energy but also visible and infrared energy. The emergence of this new material has finally fulfilled their wish.
American scientists have developed a new type of photovoltaic material, with which solar panels can be made at low cost and high efficiency. For more than 40 years, scientists have hoped to develop bulk photovoltaic materials that can utilize not only ultraviolet energy but also visible and infrared energy. The emergence of this new material has finally fulfilled their wish.
The new material was jointly developed by scientists from the University of Pennsylvania and Drexel University, and it has three outstanding advantages. First, the solar panels made from it are thinner than the silicon-based solar panels that currently dominate the market. Second, its raw materials are cheaper than those used in current high-end thin-film solar cells. Third, this material is ferroelectric, meaning its polarity can be switched on and off, which helps solar cell materials surpass the theoretical limits of current photoelectric conversion efficiency.
Part of the inefficiency of solar panels is due to particles collected from the sun scattering inside the solar cell. To make all particles flow in one direction, multiple layers of different guiding materials are needed, and each layer causes some loss, reducing the solar cell's energy efficiency. Solar cells made with the new material require fewer guiding layers, thus reducing energy loss; moreover, ferroelectric materials consume less energy to guide particles.
Scientists spent five years designing this new material, which consists of perovskite crystals made from a combination of potassium niobate and nickel-doped barium niobate. Results show that its performance far exceeds current ferroelectric materials and can absorb more than six times the solar energy. Researchers say that further refinement and adjustment of the material's composition will further improve energy efficiency.
Jonathan Spanier from Drexel University's Department of Materials Science and Engineering said, "The new material is remarkable because it is composed of inexpensive, non-toxic, and abundant elements, unlike the compound semiconductor materials used in current high-efficiency thin-film solar cells."
Researchers used a set of tools to prove that the new material allows energy to move in one direction rather than crisscrossing between layers, thus minimizing energy loss. This ability is called the bulk photovoltaic effect, known to scientists since the 1970s, but until now, it had only been observed in ultraviolet light. In fact, most of the sun's energy lies within the visible and infrared spectra. With the new material, they have finally observed this effect in visible and infrared light.
Moreover, they demonstrated that by adjusting the percentage of components in the new material, the material's bandgap can be reduced. Spanier said, "The bandgap of this material lies in the ultraviolet range, but by increasing the nickel-doped barium niobate content by just 10%, its bandgap shifts into the visible range and approaches the ideal value for solar energy conversion efficiency."
