Stability-improved perovskite solar cells through 4-tertbutylpyridine surface-passivated perovskite layer fabricated in ambient air

Methylammonium lead iodide (CH3NH3PbI3) perovskite solar cell (PSC) is one of the third generations of photovoltaic (PV) research interest in recent years. The solar cell degrades very fast in ambient air and this poses major challenge for its commercialization. Hence, this report investigates surface-passivated perovskite layer using hydrophobic material, 4-tertbutylpyridine (tBP), to modify the surface of the perovskite layer and create ambient air-resistant layer that results in improved stability of PSC performance. The fabricated films and devices were studied using UV–Vis spectrophotometer, Fourier-transform infrared (FTIR) spectrometer, Scanning Electron Microscopy (SEM), solar simulator equipped with Keithley source meter and X-ray diffractometer (XRD). The concentration of tBP was varied from 50 to 200 μl and the samples were aged in ambient air for 120 h. Eventually, the surface passivated film and the device showed improved stability performance. The champion cells of tBP-treated and untreated freshly fabricated devices showed PCE of 10.32% and 6.37%, respectively. Again, the PCE of tBP-treated and untreated devices reduced by 6.45% (10.32%–9.66%) and 60.75% (6.37%–2.50%) respectively for 120 h. Additionally, continuous light-soaking for 8 h shows that tBP-treated device is stable in its performance when compare with the tBP-untreated device.