CsPbt(2)Br inorganic perovskite has been considered as a promising candidate for application in photovoltaic devices due to its high thermal stability and reasonable bandgap of 1.92 eV. However, CsPbt(2)Br perovskite is sensitive to moisture, which remarkably deteriorates the stability of CsPbt(2)Br perovskite solar cells under the ambient conditions. Here, by using hydrophobic poly(3-hexylthiophene) (P3HT) layer in conjunction with multi-walled carbon nanotubes (MWCNTs) as the hole transporting layer, we develop a stable and high-performance carbon electrode-based CsPbt(2)Br inorganic perovskite solar cell (PSC). The P3HT-MWCNTs composites not only can prevent moisture ingress but also enhance the holes extraction and transport. A conversion efficiency up to 10.01% with a stabilized efficiency of 8.85% is achieved for the champion device. In addition, the as-prepared carbon electrode-based CsPbt(2)Br PSC exhibits an excellent long-term stability which retains similar to 85% of its initial value over 240 h under the ambient conditions (similar to 35% R.H.) without encapsulation. (C) 2019 Elsevier Inc. All rights reserved.