Enhanced efficiency and stability of quasi two-dimensional perovskite solar cells via dual additives

Quasi two-dimensional alternating cation (ACI)-type perovskites have drawn extensive research interest owing to better stability than their 3D counterparts. However, the poor charge-transfer characteristics of quasi two-dimensional perovskite film significantly impact the efficiency and stability of the devices. Herein, we propose a dual additives strategy utilizing urea and methylammonium chloride to manage the growth of (GA)(MA)5Pb5I16 perovskite films. The morphology and photoelectric characteristics manifest that the dual additives not only significantly enlarge the crystal size of the film, but also optimize the distribution of the quantum well thickness. Therefore, the solar cell based on dual additives-treated perovskite film achieves an optimal efficiency of 20.86%, far higher than 17.11% for that without additive. Moreover, the environmental stability of the quasi two-dimensional perovskite solar cells (PSCs) is raised. The unencapsulated PSCs hold 93% of the initial efficiency after being placed under environmental conditions for 1500 h. These results demonstrate that using dual additives is a promising strategy to obtain high-performance PSCs.