Synergistic Effect of Pyridine Salt Additives for Efficient and Stable Inverted Wide-Band Gap Perovskite Solar Cells

Efficient and stable inverted wide-band gap perovskite solar cells (WB PSCs) are essential to open up the potential of perovskite/silicon tandem solar cells with approaching 35% efficiency. However, the large intrinsic trap density of the wide-band gap perovskite film impedes the device performance and operational stability. Here, we introduce a 3-pyridinylmethylammonium bromide (3-PyABr) additive that can be used to passivate the intrinsic defects in the bulk perovskite film, which simultaneously solves the problems of precursor stability, device performance, and operational stability of resulted devices. The added 3-PyABr has a good interaction with uncoordinated Pb2+ and FA+ cations, thus suppressing defect-mediated non-radiative recombination. As a result, 1.68 eV WB PSCs with an efficiency of 21.03% were demonstrated, much higher than that of the control device (19.58%). The perovskite precursor solution with 3-PyABr also shows better reproducibility for high-efficient devices. Moreover, the WB PSCs with 3-PyABr exhibit enhanced operational stability, which retain 96% of its initial efficiency under continuous light soaking for 330 h without encapsulation. As a contrast, the control devices only provide 53% of their initial efficiency after 150 h. The WB PSCs also show improved thermal stability, the target device retains 93% of its initial efficiency for 500 h of aging, while the control group only provides 76% of its initial efficiency (60 °C in a N2 atmosphere).