EtOH/H2O ratio modulation on carbon for high-Voc (1.03 V) printable mesoscopic perovskite solar cells without any passivation

Abstract

With a work function close to that of gold, carbon is theoretically a good substitute for gold as a counter electrode in perovskite solar cells (PSCs). Recently, carbon-based printable mesoscopic perovskite solar cells (p-MPSCs) have attracted much attention on account of their all-screen-printing process, assembly in air-atmosphere and ultra-high stability. Herein, based on an improved Stöber strategy, a phenol-formaldehyde resin-based carbon (PFc) material is developed for p-MPSCs as counter electrodes. By the modulation of solvent polarity (EtOH/H₂O ratio) during synthesis, PFc materials with different morphologies were obtained effectively. At the optimal ratio (EtOH/H₂O = 4/3), the infiltration of the perovskite precursor in carbon electrodes was effectively improved due to the interaction between the surface functional groups (C–O/C–N and CO) of the prepared carbon material and Pb²⁺ and homogeneous porous structure. Furthermore, the open-circuit voltage (V_oc) of PFc-based p-MPSCs increased from 0.97 V to 1.03 V (without any passivation treatment) with a maximum PCE of 17.64% based on the champion device.