Organic compound passivation for perovskite solar cells with improving stability and photoelectric performance.

• A novel organic compound aminophylline (APL) is found to effectively passivate the electron transport layer. • APL can not only enhance crystal grain size, but also passivate the anti-site Pb (lead) defect. • The hydrogen bond formed by ethylenediamine (in APL) and iodide ions can assist the passivation of lead defects. Herein, we report highly efficient and stable triple cation perovskite solar cells (PSCs) with the structure of FTO/TiO 2 /perovskite/spiro-OMeTAD/Ag, in which we introduce aminophylline (APL) as an additive into the perovskite precursor solution to improve efficiency and stability. The APL additive results in increased device current density (J SC) (23.07–23.86 mA/cm2), fill factor (FF) (77.9–81.82%) and open-circuit voltage (V OC) (1.09–1.13 V), leading to an improved power conversion efficiency (PCE) of 22.11% compared to control devices (19.62%). It is worth noting that unpackaged devices employing the APL additive can remain 60% of their initial PCE in the air (at a humidity of 25–30%) after 100 days, whereas control devices merely retain less than 14% of the initial efficiency. [ABSTRACT FROM AUTHOR]