Solution-processed ITO nanoparticles as hole-selective electrodes for mesoscopic lead-free perovskite solar cells

Carbon-based mesoscopic perovskite solar cells (PSCs) are promising for printable next-generation photovoltaic applications, but the optical properties of their carbon layer limit their light harvesting efficiency. We developed solution-processable indium-tin-oxide (ITO) nanoparticles to replace carbon electrodes for mesoscopic lead-free tin-based PSCs. The ITO electrodes were fabricated via screen printing with 1, 2, 4, 6 and 8 layers corresponding to the thicknesses of 2.1-14.3 μm; tin perovskite (GA 0.2 FA 0.8 SnI 3 ) with SnF 2 (20%) and EDAI 2 (15%) (GA represents guanidinium; EDAI 2 represents ethylenediammonium diiodide) was drop-casted on the device to produce a mesoporous structure of FTO/TiO 2 /perovskite/Al 2 O 3 /ITO. The best device achieved a power conversion efficiency of 5.4% with great stability. These solution-processed ITO electrodes are a landmark to shed light on new paths for the commercialization of lead-free PSCs. All-solution-processable ITO nanoparticulate electrodes were developed to replace carbon electrodes in mesoscopic hybrid tin-based PSCs to attain a record efficiency of 5.4%.