Doping Strategy for Efficient and Stable Triple Cation Hybrid Perovskite Solar Cells and Module Based on Poly(3-Hexylthiophene)[P3HT] Hole Transport Layer

As Hole Transport Layer (HTL) for perovskite solar cells (PSCs), Poly (3-Hexylthiophene) (P3HT) has been attracting a great interest due to its low-cost, thermal stability, oxygen impermeability and strong hydrophobicity. In this work, a new doping strategy has been developed for the P3HT as HTL in triple-cation/double-halide ((FA1-x-yMAxCsy)Pb(I1-xBrx)3) mesoscopic PSCs. Photovoltaic performances and stability of solar cells show remarkable enhancement using a composition of three dopants Li-TFSI, TBP and Co(III)-TFSI reaching power conversion efficiencies of 19.25% on 0.1 cm² active area, 16.29% on 1 cm² active area and 13.3% on a 43 cm2 active area module without using any additional absorber layer or any interlayer at the PSK/P3HT interface. The results illustrate positive effect of cobalt dopant on the band structure of perovskite/P3HT interface leading to an improved hole extraction and a decrease of trap-assisted recombination. Non-encapsulated large area devices show promising air stability through keeping more than 80% of initial efficiency after 1500 hr in atmospheric conditions (RH~60%, r.t.), while encapsulated devices show more than 500 hr at 85 °C thermal stability (>80%) and 100 hr stability against continuous light soaking (>90%). The boosted efficiency and the improved stability make P3HT a good candidate for low-cost large-scale PSCs.