Bifunctional-based small molecule as multifunctional additive for improved performance of perovskite solar cells

摘要

Hybrid perovskites have great potential as light-absorbing materials, while its degradation of poor crystallization and ion migration have been the major obstacle in perovskite solar cells (PSCs). Herein, the bifunctional-based small molecule dicyandiamide (DCD) was applied as additive in the PSCs. The amino and cyano group of DCD could effectively control crystallization and passivating grain defects, resulting in the high-quality perovskite films with large grain size. In addition, the adding of DCD increases the film conductivity of perovskite active layer, which is beneficial for charge transport in perovskite film. The DCD added PSCs shows an optimal power conversion efficiency (PCE) of 19.08% with negligible hysteresis. Furthermore, the long-term stability of PSCs is significantly enhanced. The results indicate that the device's integrative performance could be efficiently improved by the synergistic effect of amino and cyano functional groups, meaning that the addition of DCD into perovskite precursor could enable this optimization.