Monolithic perovskite/organic tandem solar cells with 23.6% efficiency enabled by reduced voltage losses and optimized interconnecting layer

Due to the large chemical composition and bandgap tunability of both perovskite and organic semiconductors, perovskite/organic tandem solar cells are attractive for next-generation thin-film photovoltaics. However, their efficiency is limited by the open-circuit voltage loss of wide-bandgap perovskite subcells and the non-ideal interconnecting layers. Here we report that the passivation of nickel oxide hole-transporting layers with benzylphosphonic acid leads to the suppression of interfacial recombination, boosting the voltage up to 1.26 V in a 1.79-eV-bandgap perovskite subcell. Then, we develop an optimized interconnecting layer structure based on a 4-nm-thick sputtered indium zinc oxide layer inserted between organic bathocuproine and molybdenum oxide with enhanced electrical properties and transmittance in the near-infrared region. Through these improvements, we achieve a maximum efficiency of 23.60% (22.95% certified) in the perovskite/organic tandem solar cell. In addition, the tandem device retained 90% initial efficiency after 500 h maximum power point tracking under continuous one sun illumination.