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.