Buried organic interlayer for high-performance and stable wide-bandgap perovskite solar cells

The development of wide-bandgap perovskite solar cells (PSCs) is essential for advancing tandem solar cell technologies that exceed the Shockley-Queisser limit. In this study, two novel pyrazino[2,3-g]quinoxaline (PQ)based organic interlayers, PQ-H-H and PQ-H-F, were strategically designed and integrated at the interface between NiOx hole transport layer and the wide-bandgap perovskite layer. This incorporation aimed to improve the built-in potential of PSC through deeper highest occupied molecular orbital level and strong dipole moment of interlayer and enhance perovskite film quality through the passivation of defects and the formation of larger grains with higher crystallinity. The PSC devices incorporating PQ-H-F interlayer demonstrated the most pronounced improvement, achieving power conversion efficiency increase from 17.5 % to 20.1 %. Additionally, the incorporation of PQ-H-F effectively mitigated hysteresis and significantly improved long-term stability, retaining 90 % of the initial PCE after 500 h under ambient conditions. These results highlight the potential of PQ-based organic interlayers as a robust strategy to enhance both the performance and durability of wide-bandgap PSCs, thereby offering a pathway toward the realization of high-efficiency tandem solar cells.