Researchers at South Korea’s Ulsan National Institute of Science and Technology (UNIST) claim to have achieved a power conversion efficiency of 25.8% for a single junction perovskite solar cell without the need for passivating the surface of the perovskite layer to reduce interfacial defects.
The scientists said the result is a world record for this kind of solar cell and that the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) certified the achievement of a 25.5% efficiency for the device.
The cell was built with an interlayer between a tin(IV) oxide (SnO2) electron-transporting layer and a layer made of a halide perovskite layer by coupling chlorine-bonded SnO2 with a perovskite precursor containing chlorine. “This interlayer has atomically coherent features which enhance charge extraction and transport from the perovskite layer; and fewer interfacial defects,” the academics explained.
The defect-free connection layer is said to eliminate the risks related to passivation, which may not always provide the desired interface defect reduction, as the surface-treatment agents on the electron-transporting layer may dissolve while coating the perovskite thin film.
The cell was also able to retain around 90% of its initial efficiency after 500 hours under standard illumination. “Our findings provide guidelines for designing defect-minimizing interfaces between metal halide perovskites and electron-transporting layers,” said UNIST researcher Seok Sang-il.
The technique to develop the solar cell is presented in the study Perovskite solar cells with atomically coherent interlayers on SnO2 electrodes, which was recently published in nature.
In April, a group of researchers from UNIST and the Swiss Federal Institute of Technology Lausanne (EPFL) achieved a conversion efficiency of 25.6% in a single-junction perovskite solar cell. The result edges out the previous record of 25.2%, achieved in February by scientists at the Massachusetts Institute of Technology (MIT), and UNIST's earlier result of 25.17%, achieved in November 2020.
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