Researchers at the US Department of Energy’s National Renewable Energy Laboratory (NREL) have made a technological breakthrough and constructed a perovskite solar cell that is claimed to be both highly efficient and highly stable.
The work was done in collaboration with scientists from the universities of Toledo, Colorado–Boulder and California–San Diego.
The cell’s unique architectural structure enabled the researchers to record a certified stabilised efficiency of 24% under 1-sun illumination, making it the highest reported of its kind. The highly efficient cell also retained 87% of its original efficiency after 2400 hours of operation at 55 deg Celsius. The research results have appeared in a paper, ‘Surface reaction for efficient and stable inverted perovskite solar cells’, pubished in in the journal Nature.
Perovskite, which refers to a crystalline structure, has emerged in the last decade as an impressive PV medium. Perovskite research has been focused to a large extent on how to increase stability.
“Some [researchers] can demonstrate perovskites with high stability, but efficiency is lower,” said Zhu, a senior scientist in the Chemistry and Nanoscience Centre at NREL. “[One should aim at] high efficiency and high stability simultaneously. That’s challenging.”
The researchers used an inverted architecture, rather than the standard architecture that has to date yielded the highest efficiencies. The difference between the two types is defined by how the layers are deposited on the glass substrate. The inverted perovskite architecture is known for its high stability and integration into tandem solar cells. The NREL-led team also added a new molecule, 3-(Aminomethyl) pyridine (3-APy), to the surface of the perovskite. The molecule reacted to the formamidinium within the perovskite to create an electric field on the surface of the perovskite layer. “That suddenly gave us a huge boost of not only efficiency but also stability,” Zhu said.
The researchers reported that the 3-APy reactive surface engineering (RSE) can improve the efficiency of an inverted cell from less than 23% to greater than 25%. They also noted that RSE stands out as an effective approach to significantly enhancing the performance of inverted cells “to new state-of-the-art levels of efficiency and operational reliability.”
Funding for the NREL research came from the Centre for Hybrid Organic-Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Centre within DOE’s Office of Basic Energy Sciences, and from the DOE’s Solar Energy Technologies Office.
NREL is the US Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development. It is operated for the Energy Department by the Alliance for Sustainable Energy.