Buried interface anchoring with silane coupling agents for low voltage loss and high-efficiency wide-bandgap...

Perovskite tandem solar cells (TSCs) hold substantial promise for surpassing the efficiency limits of single-junction solar cells. Nevertheless, achieving high open-circuit voltage (V_OC) in wide-bandgap perovskite devices remains a challenge due to significant V_OC-losses. Here, we introduce a heterogeneous interface anchoring strategy aimed at enhancing interfacial properties by incorporating a silane coupling agent between the perovskite and hole transport layers. Trimethoxysilane (TMOS), an amphiphilic molecule, strengthens interfacial adhesion through enhanced chemical interactions, thereby promoting efficient hole extraction. Additionally, the terminal functional groups of TMOS molecules interact with lead ions, modulating the perovskite film crystallization and improving their overall quality. Devices treated with TMOS exhibit a marked reduction in non-radiative recombination, leading to a significant increase in V_OC. Notably, 3-cyanopropyltrimethoxysilane (CN-TMOS) optimizes the uniformity and interfacial contact of the perovskite film, achieving a V_OC of 1.345 V and a power conversion efficiency (PCE) of 19.69%. The corresponding V_OC-loss, relative to the bandgap, is reduced to 0.425 V, one of the lowest values reported for wide-bandgap perovskite single-junction solar cells. Extending this strategy to all-perovskite TSCs, we achieve a PCE of 28.45% and exceptional operational stability, retaining over 90% of the initial efficiency after 500 h of continuous operation under 1 sun illumination.