Caffeine additive based nanoarchitectonics of methylammonium lead iodide (MAPbI3) perovskite solar cell device: investigations on charge carrier properties using AC impedance spectroscopy

Caffeine (coffee powder) is introduced into methylammonium lead iodide (MAPbI(3)) to fabricate highly efficient and stable caffeine-additive based MAPbI(3) perovskite solar cell device (PSC). Perovskite solar cells with caffeine additive ratios of 1, 3, 5, 10 wt% exhibit enhanced power conversion efficiency (PCE), short circuit current density (J(SC)), open circuit voltage (V-OC), and fill factor when compared to pure MAPbI(3). In particular, the 5 wt% caffeine-MAPbI(3) perovskite solar cell device shows enhanced power conversion efficiency of 16.39% with a short circuit current density of 24.22 mAcm(-2), an open circuit voltage of 1.09 V, and a fill factor of 61.78%. This is significantly higher than the PSC devices with 1, 3, 10 wt% caffeine-MAPbI(3), and the pure MAPbI(3) PSC device. The maximum power conversion efficiency observed for pure MAPbI(3) is 10.31% with a short circuit current density of 17.07 mAcm(-2), an open circuit voltage of 1.02 V, and a fill factor of 59.21%. The caffeine-MAPbI(3) perovskite solar cell device shows 58% higher power conversion efficiency than MAPbI(3). The caffeine-MAPbI(3) PSC solar cell device retains 85% of its original efficiency over 30 days. The enhanced photovoltaic performances and stability for the caffeine-added MAPbI(3) perovskite solar cell are due to low electrical resistance values and reduced non-radiative recombination pathways in the perovskite.