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

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 FA(0.83)MA(0.17)PbI(2.51)Br(0.49) perovskite film, thus boosting the efficiency from 17.1 +/- 0.8% to 18.6 +/- 0.9% for the 0.1 cm(2) cell and from 15.5 +/- 0.5% to 16.5 +/- 0.6% for the 1.0 cm(2) cell. The champion cell shows efficiencies of 20.0% and 17.6% with active areas of 0.1 and 1.0 cm(2), 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.