A facile route toward carbon paste modification, for high-performing bi-functional hole extracting counter electrodes in C-based PSCs

Applied Physics Letters, Volume 118, Issue 14, April 2021. An increase in the photovoltaic properties of carbon (C)-based perovskite solar cells (PSCs) of the triple mesoscopic structure has been achieved, by using a simple, solution-based method, to enhance the charge transport properties of the C electrode. In this context, a variety of Ni precursor solutions have been inserted in the typical carbon black/graphite paste. Space charge limited current measurements have revealed a higher hole mobility for the modified pastes. The power conversion efficiency of the optimized PSC, which has been prepared entirely under ambient conditions, in addition to being hole transport layer free, reaches ∼9.9%, which is higher than 9.1% for the reference C paste electrode. The results and beneficial effect of Ni incorporation have also been confirmed by electrochemical impedance spectroscopy and incident photon to current conversion efficiency measurements. Our results bring out a simple and low-cost method to improve the performance of C-based energy-related devices.