High-performance carbon electrode-based CsPbI₂Br inorganic perovskite solar cell based on poly(3-hexylthiophene)-carbon nanotubes composite hole-transporting layer

CsPbI₂Br 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, CsPbI₂Br perovskite is sensitive to moisture, which remarkably deteriorates the stability of CsPbI₂Br 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 CsPbI₂Br 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 CsPbI₂Br PSC exhibits an excellent long-term stability which retains ∼85% of its initial value over 240 h under the ambient conditions (∼35% R.H.) without encapsulation.