Constructing low-dimensional perovskite network to assist efficient and stable perovskite solar cells

We proposed a concept of a discontinuous LD network perovskite on top of a 3D perovskite film, enabling efficient charge carrier transport. This led to a champion PCE of 24.6% and devices with LD network perovskite exhibit enhanced humidity and thermal stability. The use of low-dimensional (LD) perovskite materials is crucial for achieving high-performance perovskite solar cells (PSCs). However, LD perovskite films fabricated by conventional approaches give rise to full coverage of the underlying 3D perovskite films, which inevitably hinders the transport of charge carriers at the interface of PSCs. Here, we designed and fabricated LD perovskite structure that forms net-like morphology on top of the underlying three-dimensional (3D) perovskite bulk film. The net-like LD perovskite not only reduced the surface defects of 3D perovskite film, but also provided channels for the vertical transport of charge carriers, effectively enhancing the interfacial charge transfer at the LD/3D hetero-interface. The net-like morphological design comprising LD perovskite effectively resolves the contradiction between interfacial defect passivation and carrier extraction across the hetero-interfaces. Furthermore, the net-like LD perovskite morphology can enhance the stability of the underlying 3D perovskite film, which is attributed to the hydrophobic nature of LD perovskite. As a result, the net-like LD perovskite film morphology assists PSCs in achieving an excellent power conversion efficiency of up to 24.6% with over 1000 h long-term operational stability.