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Hybrid organo-metal halide perovskite solar cells (PSCs) are promising candidates for next generation photovoltaic device primarily due to their high efficiency, printability and low cost. PSCs have exhibited externally verified power conversion efficiencies (PCE) exceeding 25% outclass from 3.8% in 2009, which have encouraged recent efforts on scalable coating technique in PSCs towards manufacturing. However, devices fabricated by scalable techniques are still lagged the state-of-the-art spin coated devices because the power conversion efficiency (PCE) is highly dependent on the morphology and crystallization kinetics under a controlled environment, and delicate solvent system engineering.
In this talk, we present the recent works using in-situ technique to guide the development of high performance PSCs using blade coating technology.
(a). Via a laminar air-knife assisted room temperature meniscus coating approach to control the drying kinetics during the solidification process, we recently manufacturing friendly, antisolvent-free room-temperature coating of hysteresis-free PSCs with power conversion efficiency (PCE) of 20.26% for 0.06 cm2 and 18.76% for 1 cm2 devices. Moreover, this approach offers a solid model platform for in-situ UV-vis and microscope investigation of the perovskite film drying kinetics.
(b) One step further, based on the widest studied champion perovskite solution system DMF-DMSO, we report air-knife assisted fabrication of perovskite solar cell in AMBIENT condition at high relative humidity of 55±5%. In-depth in-situ time-resolved UV-vis spectrometry is carried out to investigate the impact of solvent removal and crystallization rate, which are proven to be a critical factor on influencing the crystallization kinetics and morphology due to moisture attack. The UV-vis spectrometry also enables accurate determination of wet precursor film thickness – a key parameter for fabrication. Anti-solvent free, high humidity ambient coating of hysteresis-free PSCs with PCE of 21.1% and 18.0% are demonstrated for 0.06 cm2 and 1 cm2 devices, respectively. These PSCs coated in high humidity ambient conditions also show comparable stability with those made in N2 glovebox.
(c) The room temperature meniscus coating of high-quality perovskite films incorporated with a multifunctional sulfobetaine based zwitterionic surfactant. Systematic in-situ studies uncover the perovskite crystallization pathway and emphasize the surfactant's synergistic role in film construction, crystallization kinetics modulation, defect passivation, and moisture barrier protection. This strategy is applicable across perovskite compositions and device architectures with the enhanced power conversion efficiencies up to 22%. In addition, this approach significantly improves the stability of perovskite films and devices under different aging conditions.
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