Solar panels, also known as photovoltaics, rely on semiconductor devices, or solar cells, to convert energy from the sun into electricity.
To generate electricity, solar cells need an electric field to separate positive charges from negative charges. To get this field, manufacturers typically dope the solar cell with chemicals so that one layer of the device bears a positive charge and another layer a negative charge. This multilayered design ensures that electrons flow from the negative side of a device to the positive side — a key factor in device stability and performance. But chemical doping and layered synthesis also add extra costly steps in solar cell manufacturing.
Now, a research team led by scientists at DOE’s Lawrence Berkeley National Laboratory (Berkeley Lab), in collaboration with UC Berkeley, has demonstrated a unique workaround that offers a simpler approach to solar cell manufacturing: A crystalline solar material with a built-in electric field — a property enabled by what scientists call “ferroelectricity.” The material was reported earlier this year in the journal Science Advances.
The new ferroelectric material — which is grown in the lab from cesium germanium tribromide (CsGeBr3 or CGB) — opens the door to an easier approach to making solar cell devices. Unlike conventional solar materials, CGB crystals are inherently polarized, where one side of the crystal builds up positive charges and the other side builds up negative charges, no doping required.
In addition to being ferroelectric, CGB is also a lead-free “halide perovskite,” an emerging class of solar materials that have intrigued researchers for their affordability and ease of synthesis compared to silicon. But many of the best-performing halide perovskites naturally contain the element lead. According to other researchers, lead remnants from perovskite solar material production and disposal could contaminate the environment and present public health concerns. For these reasons, researchers have sought new halide perovskite formulations that eschew lead without compromising performance.
Read More: Scientists Grow Lead-Free Solar Material With Built-In Switch