Interface modification and crystallization control of efficient and stable perovskite solar cells using dicyandiamide

Abstract

Tin dioxide (SnO₂) is a promising electron transport material for perovskite solar cells (Pero-SCs), but its intrinsic defects, mainly dangling bonds, accelerate degradation of perovskite layers. To address this, we utilized dicyandiamide (DCD), a small molecule featuring bifunctional groups –NH₂ and –CN, as an interfacial modification layer. The introduction of DCD not only effectively passivated SnO₂ defects through DCD's –CN groups, thereby improving the arrangement of interface energy level and the conductivity of the SnO₂ film, but also facilitated the formation of high-quality perovskite films at the newly created buried interface in n–i–p solar cells, attributed to the ameliorating influence of DCD's –NH₂ groups. Consequently, the power conversion efficiency (PCE) of the corresponding Pero-SCs was substantially improved from 21.28% to 24.50% upon DCD incorporation. Moreover, unencapsulated devices demonstrated enhanced stability, retaining 93.2% of their initial PCE after 720 hours of storage at controlled humidity (RH = 30–40%).