Professor Wang Zhiping and his team from the School of Physics and Technology at Wuhan University have published a paper titled A molecularly engineered electron-selective self-assembled monolayer enhances quasi-Fermi level splitting in inverted perovskite solar cells in Nature Energy, advancing solar energy technology.

Perovskite solar cells are renowned for their high photoelectric conversion efficiency and cost-effectiveness. However, insufficient quasi-Fermi level splitting at interfaces, particularly the perovskite/C60 interface, remains a critical bottleneck for improving open-circuit voltage and overall performance.

The team found that when interfaces are passivated with low recombination rates, fast extraction depletes interface carrier density, limiting quasi-Fermi level splitting and open-circuit voltage.

The team introduced an innovative "molecular brake" approach and engineered an electron-selective self-assembled monolayer (SAM), an N-type SAM called 3PDPA, at the perovskite/C60 interface.

This molecular layer reduces electron extraction rates and passivates interface defects by anchoring uncoordinated lead ions and forming a hydrogen-bond network. π–π interactions improve contact with the C60 layer, achieving a synergistic effect of slow extraction and strong passivation.

Experimental results revealed that inverted perovskite solar cells incorporating the 3PDPA interface achieved photoelectric conversion efficiencies of 26.82 percent and 21.2 percent at bandgaps of 1.53 eV and 1.77 eV, respectively.

Compared to traditional ammonium halide passivators, the new SAM molecules demonstrated superior long-term stability, maintaining 90 percent of their initial performance after approximately 1,000 hours under ISOS-L-3 standard testing.