Improving Hole‐Conductor‐Free Fully Printable Mesoscopic Perovskite Solar Cells’ Performance with Enhanced Open‐Circuit Voltage via the Octyltrimethylammonium Chloride Additive

Abstract

Hole‐conductor‐free fully printable mesoscopic perovskite solar cells (MPSCs) based on mp‐TiO2/mp‐ZrO2/carbon triple mesoscopic layers are competitive candidates among various rapidly developed PSCs for future photovoltaic applications due to the characteristics of low‐cost, easy upscaling, and superior stability. However, the open‐circuit voltage (VOC) loss in printable MPSCs is relatively large compared to that in conventional PSCs, deteriorating the power conversion efficiency (PCE). Herein, the VOC loss is reduced by the octyltrimethylammonium chloride (OTAC) additive. OTAC is found to upshift the Fermi level of TiO2 and passivate trap states in bulk MAPbI3 perovskite, thus optimizing the energy‐level alignment of the TiO2/perovskite heterojunction and suppressing nonradiative recombination in devices. As a result, MPSCs deliver the highest PCE of 16.53% with an improved VOC of 1007 mV. The work demonstrates a facile strategy to reduce the VOC loss in printable MPSCs by simultaneously optimizing the energy‐level alignment and suppressing nonradiative recombination.