Abstract
The performance of perovskite solar cells with inverted polarity (p-i-n) is still limited by recombination at their electron extraction interface, which also lowers the power conversion efficiency (PCE) of p-i-n perovskite-silicon tandem solar cells. A MgF
x
interlayer with thickness of ~1 nanometer at the perovskite/C
60
interface favorably adjusts the surface energy of the perovskite layer through thermal evaporation, which facilitates efficient electron extraction and displaces C
60
from the perovskite surface to mitigate nonradiative recombination. These effects enable a champion open-circuit voltage of 1.92 volts, an improved fill factor of 80.7%, and an independently certified stabilized PCE of 29.3% for a monolithic perovskite-silicon tandem solar cell ~1 square centimeter in area. The tandem retained ~95% of its initial performance after damp-heat testing (85°C at 85% relative humidity) for >1000 hours.
A fluoride boost
The wide-bandgap perovskite layer in perovskite-silicon tandem solar cells is still limited by high interface recombination at the electron extraction interface. Liu
et al
. show that adding an ultrathin magnesium fluoride interlayer between the perovskite and C
60
electron transport layer during growth facilitates mitigated nonradiative recombination. An analysis of electronic structural data showed that conduction band bending of the perovskite and C
60
facilitated electron extraction. A monolithic perovskite-silicon tandem solar cell with a certified power conversion efficiency of 29.3% retained about 95% of its initial performance for 1000 hours. —PDS
The surface energy of the perovskite layer at the C
60
interface is favorably adjusted with a magnesium fluoride interlayer.