Defect Dynamics and Solution-Processed Interconnects in Perovskite-Organic Tandem Solar Cells

Perovskite and organic semiconductors exhibit analogous properties, including bandgap tunability, low-temperature solution processing, and high potential for lightweight applications. These similarities render them highly attractive for being integrated in multijunction architecture: perovskite-organic tandem solar cells (POTSCs). Nevertheless, the efficiency of POTSCs is limited by electrical losses, which stem from both the wide-bandgap (WBG) perovskite layers and the interconnecting layers (ICLs) between two subcells. These two essential components also constrain the tandem device stability. In this study, the underlying cause of open-circuit voltage (V_OC) losses in WBG perovskites is identified, which is ascribed to the presence of mobile defects distributed at surface regions. An employ effective passivation agent with functional chemical groups is further employed to facilitate the healing of the mobile defects, thereby enhancing the V_OC to 1.35 V for WBG perovskite solar cells with a bandgap of 1.81 eV. Subsequently, solution-processed graphene oxide layer ICLs are developed for tandem application, which not only reduces electrical losses but also improves tandem device stability. The synergistic integration of these two strategies has enabled POTSCs to surpass 25% efficiency while simultaneously achieving enhanced operational stability.