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Interlayer Engineering for Flexible Large-Area Planar Perovskite Solar Cells

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journal contribution
posted on 31.12.2019 by Jia Li, Guifang Han, Kurt Vergeer, Herlina Arianita Dewi, Hao Wang, Subodh Mhaisalkar, Annalisa Bruno, Nripan Mathews
Hybrid metal halide perovskite solar cells (PSCs) have consistently demonstrated high power conversion efficiency (PCE), although the best performing PSCs mostly employ high-temperature (500 °C) processed compact and mesoporous TiO2. Instead, low-temperature processed PSCs are desirable for implementation on flexible substrates and tandem solar cells. Here, we present a new method to achieve high efficiency flexible planar PSCs based on a low-temperature processed nonaqueous sol–gel route that synthesized TiO2 and a guanidinium iodide (GuaI) salt passivation treatment of the perovskite film. We fabricate both rigid and flexible triple-cation perovskite (Cs0.05(MA0.17FA0.83)0.95Pb­(I0.85Br0.15)3, Eg ∼ 1.58 eV) PSCs, achieving PCEs of 19.8% and 17.0% on glass and polyethylene naphtholate (PEN) substrates, respectively. At the same time, rigid and flexible high-bandgap double cation (FA0.85Cs0.15Pb­(I0.7Br0.3)3, Eg ∼ 1.72 eV) PSCs reached a PCE of 18.0% and of 15.8%. Moreover, large area (1 cm2) ∼1.58 eV and ∼1.72 eV PSCs achieved PCEs of 18.2% and 16.7% PCE on glass substrates and of 16.2% and 13.9% on PEN substrates, demonstrating the high uniformity of all the solar cell layers.