Caffeine Doped Perovskite Solar Cells Without Hole Transporting Material

Abstract

Perovskite photovoltaics is one of the fastest growing research field in materials science. The effect of caffeine in the absorber structure of the Perovskite Solar Cells (PSCs) was studied systematically in this study. Caffeine was added at different concentration ratio of 0.3 ml (S1), 0.6 ml (S2), 0.9 ml (S3) and 1.2 ml (S4) while the PSCs without caffeine content is denoted as C. The as-prepared PSCs were characterized via Scanning Electron Microscopy (SEM), Ultraviolet-Visible Spectroscopy (UV-vis), Profiler and (Current density - Voltage) J-V analysis techniques. The SEM results shows a nucleated orientation with average diameter of 185.16±0.2 µm. Optical analysis shows a red shift within the visible light spectrum, indicated a more visible lights are being absorbed, thus, a potential photoanode for perovskite solar cells applications. The profiler results shows the as-prepared nanomaterials is within the range of ⁓40 nm. The electrical performance of PSCs, caffeine nanoparticles (NPs) was observed to have enhanced the PSCs by improving Short circuit current (Jsc), Open circuit voltage (Voc), Field factor (FF) and Power conversion efficiency (PCE) of the fabricated devices. The highest performing PSCs was observed in device S1 with PCE of 9.57%, Jsc of 15.71 mAcm-2 , Voc 0.94 and FF 0.65, which shows ~1.57 times improvement in PCE over the control device (C). The addition of caffeine NPs increased the rate of exciton generation and the probability of exciton dissociation, enhancing charge separation, reducing the recombination rate as well as facilitating carrier transport in the device. Thus, in this study, device S1 showed an improved PCE of 9.57%.