Origination of Anomalous Current Fluctuation in Perovskite Solar Cells

Perovskite solar cells (PSCs) have been rapidly crowded into the emerging photovoltaics, exhibiting soaring efficiencies over 25%. There are unusual characteristics that have emerged in the progression of these solar cells, such as anomalous current hysteresis and light soaking effect. Here, we first identify a current fluctuation phenomenon in PSCs and show the feature of current fluctuation. Scan derived power conversion efficiency is seriously interrupted by the current fluctuation under working conditions. The hole transport material (HTM) 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) in PSCs undergoes severe morphological deformation along with the storage time, which results in this current fluctuation phenomenon. Li-bis(trifluoromethanesulfonyl)-imide (LiTFSI) and 4-tert-butylpyridine (tBP) as additives within the spiro-OMeTAD layer induce large pinholes across the whole HTM after the tBP additive escaped and the LiTFSI additive aggregated. These aggregated fre...