Effects of Chemical Bath-Deposited TiO2 Compact Layer on the Performance of the Fully Screen-Printable Hole-Transport Material-Free Mesoscopic Perovskite Solar Cells with a Carbon Electrode

The optimization of a compact layer in perovskite solar cells (PSCs) strongly influences the device performance. In this work, we prepared a TiO 2 compact layer through simple hydrolysis of aqueous TiCl 4 solution and have investigated the influence of the TiO 2 compact layer on the performance of the fully screen-printable hole-transport material (HTM)-free PSCs with a carbon electrode. The PSC prepared from the TiO 2 compact layer made by hydrolyzing TiCl 4 precursor solution for 70 min achieved the highest device performance, with a short-circuit current density of 20.01 mA cm −2 , an open-circuit voltage of 0.96 V, a fill factor of 0.60 and a power conversion efficiency of 11.53%. Cyclic voltammetry, steady-state photoluminescence spectroscopy and electrochemical impedance spectroscopy were performed to study the charge transfer process in the device. The obtained results suggest that the compact layer in the solar cell structure without HTM plays a decisive role. The improved device performance was attributed to the increase of the charge transport ability and a charge recombination resistance in the TiO 2 compact layer.