Science News: 2021 Adv. Energy Mater. (IF 29.368), over 22% PCE! MA-free and Br-free PSCs

　　Advanced Energy Materials (IF 29.368) recently published a research result. The research team used n-propylammonium chloride (PACl) as a substitute for methylammonium chloride (MACl) to obtain a more stable and efficient α-phase formamidinium lead iodide (FAPbI₃) perovskite solar cell (PSC).

　　In order to achieve high efficiency for perovskite solar cells based on FAPbI₃, scientists usually add methylammonium chloride (MACl) to the precursor solution, hoping to achieve phase stability and improve grain size and crystallinity through MACl. However, the instability of MA in perovskite limits the long-term stability of the device.

　　In this study, the researchers used n-propylammonium chloride (PACl) instead of MACl to increase the grain size of the perovskite after adding PACl. Unlike the MA cation, the propylammonium cation ion could passivate the grain boundary, thereby reducing the band gap change. Through the solar simulator and standard battery calibration, the research team analyzed the photovoltaic characteristics of solar cells. The researchers found that the perovskite solar cell using 20 mol% PACl additive achieved a power conversion efficiency of more than 22.2%, which is the most efficient of the MA-free and Br-free perovskite solar cells. In addition to the EQE (External Quantum Efficiency) spectrum analysis of solar cells, the quantum efficiency measurement system also provides a comparison of Jsc (short-circuit current density) for the short-circuit current of solar cells under the solar simulator to prove The authenticity of the experiment.

　　The results of the study also showed that the carrier life of the perovskite with PACI increased from 405 ns to 2110 ns, a significant increase of more than five times; while the MACl additive only increased the carrier life by four times. In addition, due to the barrier layer formed in situ on the massive perovskite, PACI is much more stable to moisture than MACl.