A donor–acceptor-type hole-selective contact reducing non-radiative recombination losses in both subcells towards efficient all-perovskite tandems

The efficiency of all-perovskite tandem solar cells has surpassed that of single-junction perovskite solar cells, yet they still suffer from interfacial non-radiative recombination losses. Charge-selective materials that can reduce such losses as well as fabrication cost “applicable” to both subcells should be developed. Here we design a donor–acceptor-type molecule, MPA2FPh-BT-BA (2F), as a hole-selective contact suitable to both wide-bandgap (WBG) and low-bandgap (LBG) subcells for high-performance all-perovskite tandem solar cells. In the WBG cell, 2F enables efficient hole extraction and minimizes interfacial non-radiative recombination losses by passivating interfacial defects. In the LBG cell, 2F suppresses interfacial losses, regulates the crystal growth and enhances Sn–Pb perovskite film quality. As a result, 2F-treated WBG and LBG devices yield efficiencies of 19.33% (certified 19.09%) and 23.24%, respectively, enabling monolithic all-perovskite tandem solar cells with an efficiency of 27.22% (certified 26.3%) and improved operational stability.