Influences of Spiro-MeOTAD Hole Transport Layer on the Long-term Stabilities of Perovskite-based Solar Cells

On the basis of concerted research efforts worldwide, there is no doubt that outstanding power conversion efficiency (PCE) can be achieved in perovskite solar cells. However, to move forward this technology towards commercialization, developments of strategies to achieve long term stability is important. At OIST, a team of researchers in the Energy Materials and Surface Sciences Unit has been making concerted efforts to develop processes aiming at high PCE, high-throughput, minimum batch-to-batch variation, compatible with large-area perovskite solar cells and modules, low toxicity, and long-term stability. Optimization of hole transport materials (HTMs) is important for enhancing solar power conversion efficiency and improving stability. In this talk, we will present our latest understanding of fundamental interactions between Li-bis(trifluoromethanesulfonyl)-imide (LiTFSI), 4-tert-butylpyridine (t-BP) and spiro-MeOTAD and how different gas exposures (e.g., exposure to O₂, H₂O, N₂) influences electronic structures and conductivity of such HTM films. In addition, we will propose further strategies to improve perovskite solar cell performance and stability.