Artificial p–n-like junction based on pure 2D organic–inorganic halide perovskite structure having naphthalene diimide acceptor moieties

2D organic–inorganic perovskites are an emerging class of materials with great potential for optoelectronics since a wide variety of large functional chromophores can be regularly incorporated. Among this new type of materials, hybrid perovskite systems incorporating strong electron acceptor molecules are considered as a promising approach to designing a new type of functional 2D perovskites for optoelectronics. In this work, a rare example of organic–inorganic 2D perovskite incorporating strong acceptors such as naphthalene diimide (NDI) building blocks between inorganic sheets is presented. This hybrid architecture forms highly air-stable thin films with a structure consisting of inorganic perovskite monolayers of metal-halide octahedra separated by bilayers of NDI-based organic cations. The presence of strong electron-accepting moieties in this multifunctional donor–acceptor hybrid heterostructure leads to a rare type II heterojunction in which the excitons can be efficiently dissociated via the electron-transfer process and in which holes and electrons can be easily confined in the inorganic and organic sublayers, respectively. Such an ultimate p–n heterojunction shows improved photoconduction properties with a photocurrent multiplied by ≈40 under white-light illumination in comparison to a similar 2D perovskite structure containing optically and electrically inert alkyl chains as organic components.