Researchers from the Institute of Microelectronics of the Chinese Academy of Sciences and the North China Electric Power University developed an in situ epitaxial blocking structure on the wide-bandgap mixed-halide perovskite, which significantly suppressed the phase segregation of perovskite and improved the efficiencies of both single-junction and four-terminal solar cells. This work was published in Joule.
Wide-bandgap mixed-halide perovskites show promise of realizing efficient tandem solar cells but at present suffer from photoinduced phase segregation, which deteriorates their device efficiency and stability.
In this work, the researchers implemented a highly crystalline blocking structure to control phase segregation by in situ epitaxial growth onto a mixed-halide wide-bandgap perovskite.
Due to the released lattice strain, the improved potential barrier of halide ion migration, and the reduced defects by the blocking structure, the mixed-halide perovskite solar cell with a bandgap of 1.65 eV demonstrated a remarkable open-circuit voltage of 1.25 V (maximum 1.26 V) with a champion efficiency of 21.80% (certified 21.52%). Under continuous 1-sun white light emitting diode (LED) illumination, the device stored in nitrogen glovebox retained 90% of initial efficiency after 1080 hours.
The semitransparent device using the transparent indium tin oxide (ITO) back electrode yielded a state-of-the-art certificated efficiency of 19.15%, and a four-terminal tandem device was constructed by overlaying it on a silicon solar cell, obtaining a high efficiency of 28.83%.
The work is of great significance for the development of perovskite-based tandem photovoltaics.
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