Interface Modification via a Hydrophobic Polymer Interlayer for Highly Efficient and Stable Carbon-Based Inorganic Perovskite Solar Cells

The Serious interfacial recombination and low-efficient hole extraction at the interface of the carbon electrode and perovskite film have strikingly limited the performance improvement of carbon-based inorganic perovskite solar cells (PSCs). Here, hydrophobic poly(3-hexylthiophene) (P3HT) and polystyrene (PS) are employed as the interlayer to modify the interface of the CsPbIBr2 perovskite and the carbon electrode for enhancing the hole extraction and reducing the interfacial recombination. The effect of the PS and P3HT interlayer on the stability of the CsPbIBr2 perovskite film and the performance of carbon-based devices are systemically investigated. Both PS and the P3HT interlayer remarkably enhance the stability of the CsPbIBr2 perovskite film by inhibiting the intrusion of ambient moisture. However, the incorporation of the PS interlayer deteriorates the efficiency of the device, mainly owing to the low tunneling rate of the holes within the insulated PS layer. By contrast, introduction of the P3HT interlayer greatly improves the performance of the carbon-based CsPbIBr2 cells. The cell with the P3HT interlayer delivers a high power conversion efficiency of 7.47%, largely increased by 36% compared with the efficiency for the control device. Additionally, the P3HT interlayer greatly promotes the long-term stability of carbon-based CsPbIBr2 PSCs in ambient conditions.