Improved Efficiency and Stability of Perovskite Solar Cells Induced by CO Functionalized Hydrophobic Ammonium‐Based Additives

• Published in: Advanced materials (Weinheim) 2018-01, Vol.30 (3), p.n/a
• Main Authors: Wu, Zhifang, Raga, Sonia R., Juarez‐Perez, Emilio J., Yao, Xuyang, Jiang, Yan, Ono, Luis K., Ning, Zhijun, Tian, He, Qi, Yabing
• Format: Article
• Language: English
• Subjects: Additives; Carrier recombination; Cations; Current carriers; Efficiency; hysteresis‐free solar cells; large‐area solar cells; Lewis acid; Materials science; moisture stability; perovskite solar cells; Photovoltaic cells; Solar cells; Stability; triple cations
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201703670

Because of the rapid rise of the efficiency, perovskite solar cells are currently considered as the most promising next‐generation photovoltaic technology. Much effort has been made to improve the efficiency and stability of perovskite solar cells. Here, it is demonstrated that the addition of a novel organic cation of 2‐(6‐bromo‐1,3‐dioxo‐1H‐benzo[de]isoquinolin‐2(3H)‐yl)ethan‐1‐ammonium iodide (2‐NAM), which has strong Lewis acid and base interaction (between CO and Pb) with perovskite, can effectively increase crystalline grain size and reduce charge carrier recombination of the double cation FA0.83MA0.17PbI2.51Br0.49 perovskite film, thus boosting the efficiency from 17.1 ± 0.8% to 18.6 ± 0.9% for the 0.1 cm2 cell and from 15.5 ± 0.5% to 16.5 ± 0.6% for the 1.0 cm2 cell. The champion cell shows efficiencies of 20.0% and 17.6% with active areas of 0.1 and 1.0 cm2, respectively. Moreover, the hysteresis behavior is suppressed and the stability is improved. The result provides a promising route to further elevate efficiency and stability of perovskite solar cells by the fine tuning of triple organic cations. A new organic additive (2‐NAM) is introduced into the perovskite film. The introduction of this additive boosts the efficiency from 17.1 ± 0.8% to 18.6 ± 0.9% for the 0.1 cm2 area cells and from 15.5 ± 0.5% to 16.5 ± 0.6% for the 1.0 cm2 area cells. Moreover, the hydrophobic nature of this additive effectively reduces the influence from moisture, thus enhancing the solar cell stability.