Gallant, B.M.; Holzhey, P.; Smith, J.A.; Choudhary, S.; Elmestekawy, K.A.; Caprioglio, P.; Levine, I.; Sheader, A.A.; Hung, E.Y.H.; Yang, F.; Toolan, D.T.W.; Kilbride, R.C.; Zaininger, K.A.; Ball, J.M.; Christoforo, M.G.; Noel, N.K.; Herz, L.M.; Kubicki, D.J.; Snaith, H.J.: A green solvent enables precursor phase engineering of stable formamidinium lead triiodide perovskite solar cells. Nature Communications 15 (2024), p. 10111/1-14
10.1038/s41467-024-54113-4
Open Access Version
Abstract:
Perovskite solar cells (PSCs) offer an efficient, inexpensive alternative to current photovoltaic technologies, with the potential for manufacture via high-throughput coating methods. However, challenges for commercial-scale solution-processing of metal-halide perovskites include the use of harmful solvents, the expense of maintaining controlled atmospheric conditions, and the inherent instabilities of PSCs under operation. Here, we address these challenges by introducing a high volatility, low toxicity, biorenewable solvent system to fabricate a range of 2D perovskites, which we use as highly effective precursor phases for subsequent transformation to α-formamidinium lead triiodide (α-FAPbI3), fully processed under ambient conditions. PSCs utilising our α-FAPbI3 reproducibly show remarkable stability under illumination and elevated temperature (ISOS-L-2) and “damp heat” (ISOS-D-3) stressing, surpassing other state-of-the-art perovskite compositions. We determine that this enhancement is a consequence of the 2D precursor phase crystallisation route, which simultaneously avoids retention of residual low-volatility solvents (such as DMF and DMSO) and reduces the rate of degradation of FA+ in the material. Our findings highlight both the critical role of the initial crystallisation process in determining the operational stability of perovskite materials, and that neat FA+-based perovskites can be competitively stable despite the inherent metastability of the α-phase.